Work out the value of \(\sin ABC\) Give your answer in the form \(\dfrac{m}{n}\) where \(m\) and \(n\) are integers. (4)
Mark scheme
Answer
Mark
Mark scheme
\(\dfrac{65}{214}\)
B1
for \(\sin 30 = 0.5\)
P1
for use of the sine rule with values substituted, eg \(\dfrac{6.5}{\sin ABC} = \dfrac{10.7}{\sin 30}\) oe
P1
for \((\sin ABC =)\ \dfrac{6.5 \times \sin 30}{10.7}\) oe or for a complete process to find \(\sin ABC\), eg \((\sin ABC =)\ \dfrac{6.5 \times [0.5]}{10.7}\) oe
A1
for \(\dfrac{65}{214}\) oe eg \(\dfrac{325}{1070}\)
Additional guidance
Answer of \(\dfrac{3.25}{10.7}\) or \(\dfrac{6.5}{21.4}\) gets 3 marks
Where [0.5] is their value of \(\sin 30\)
Answer must be in the form \(\dfrac{m}{n}\) where \(m\) and \(n\) are integers
the length of \(AB\) : the length of \(CD = 2 : 3\)
Find the length of \(AB\). (5)
Mark scheme
Answer
Mark
Mark scheme
17.6
P1
for correct trig statement, eg \(\sin 30 = \dfrac{h}{6}\)
P1
for complete process to find \(h\), eg \(6 \times \dfrac{1}{2}\ (= 3)\)
P1
for correct substitution into the area of a trapezium formula, eg \(\dfrac{1}{2}(a + b) \times \text{``}3\text{''} = 66\) or \(a + b = 44\) or \(\dfrac{1}{2}(2x + 3x) \times h = 66\)
P1
for complete correct process to find the length of \(AB\), eg \(\left[\dfrac{66 \times 2}{3} \div (2 + \text{``}3\text{''})\right] \times 2\)
14 Find the exact value of \(\tan 30^\circ \times \sin 60^\circ\) Give your answer in its simplest form. (2)
Mark scheme
Answer
Mark
Mark scheme
\(\dfrac{1}{2}\)
M1
for \(\dfrac{1}{\sqrt{3}} \times \dfrac{\sqrt{3}}{2}\) or \(\dfrac{\sqrt{3}}{3} \times \dfrac{\sqrt{3}}{2}\) or \(\left(\dfrac{1}{2} \div \dfrac{\sqrt{3}}{2}\right) \times \dfrac{\sqrt{3}}{2}\) OR \(\tan 30 = \dfrac{1}{\sqrt{3}}\) oe or \(\sin 60 = \dfrac{\sqrt{3}}{2}\)
\(ABEF\) and \(CBED\) are congruent parallelograms where \(AB = BC = x\) cm. \(P\) is the point on \(AF\) and \(Q\) is the point on \(CD\) such that \(BP = BQ = 10\) cm.
18 Show that \(\quad \dfrac{\sin 30^\circ \times \cos 45^\circ}{\tan 60^\circ} \quad\) can be written in the form \(\dfrac{\sqrt{a}}{b}\)
where \(a\) and \(b\) are integers. [3 marks]
Mark scheme
Answer
Mark
Comments
\(\sin 30 = \dfrac{1}{2}\) and \(\cos 45 = \dfrac{1}{\sqrt{2}}\) or \(\dfrac{\sqrt{2}}{2}\) and \(\tan 60 = \sqrt{3}\)
M2
oe eg \(\dfrac{\frac{1}{2} \times \frac{1}{\sqrt{2}}}{\sqrt{3}}\) or \(\dfrac{\frac{1}{2} \times \frac{\sqrt{2}}{2}}{\sqrt{3}}\) or \(\dfrac{1}{2\sqrt{6}}\) may be seen in a table implied by position in a calculation eg \(\dfrac{1}{2} \times \dfrac{1}{\sqrt{2}} \times \dfrac{1}{\sqrt{3}}\) is correct for M2 M1 1 or 2 correct values
\(\dfrac{\sqrt{6}}{12}\) with all three correct values seen
A1
oe in the form \(\dfrac{\sqrt{a}}{b}\) eg \(\dfrac{\sqrt{24}}{24}\) condone \(a = 6\) and \(b = 12\) with all three correct values seen
Additional guidance
Allow \(\sqrt{1}\) for 1 throughout
Allow, eg \(\dfrac{\sqrt{3}/2}{1/2}\) for tan 60
Correct answer from \(\dfrac{\frac{1}{\sqrt{2}} \times \frac{1}{2}}{\sqrt{3}}\) scores only M1 for tan 60 unless the correct values are attributed to sin 30 and cos 45 elsewhere in the working
Do not allow further work eg \(\dfrac{\sqrt{6}}{12} = \dfrac{\sqrt{1}}{2}\) (with all three correct values seen)
25 Show that the value of \(\quad 6\sin 30^\circ + 2\cos 30^\circ \times 4\tan 30^\circ \quad\) is an integer. [4 marks]
Mark scheme
Answer
Mark
Comments
Alternative method 1: substitutes values
\((\sin 30^\circ =)\ \dfrac{1}{2}\) or \(6\sin 30^\circ = 3\) or \((\cos 30^\circ =)\ \dfrac{\sqrt{3}}{2}\) or \(2\cos 30^\circ = \sqrt{3}\) or \((\tan 30^\circ =)\ \dfrac{1}{\sqrt{3}}\) or \(\dfrac{\sqrt{3}}{3}\) or \(4\tan 30^\circ = \dfrac{4}{\sqrt{3}}\) or \(\dfrac{4\sqrt{3}}{3}\)
M1
may be seen beside the given expression or in a table
\(6\left(\dfrac{1}{2}\right)\) and \(2\left(\dfrac{\sqrt{3}}{2}\right)\) and \(4\left(\dfrac{1}{\sqrt{3}}\right)\) or \(6\left(\dfrac{1}{2}\right)\) and \(2\left(\dfrac{\sqrt{3}}{2}\right)\) and \(4\left(\dfrac{\sqrt{3}}{3}\right)\) or \(\dfrac{6}{2}\) and \(\dfrac{2\sqrt{3}}{2}\) and \(\dfrac{4\sqrt{3}}{3}\)
M1dep
oe
Processing at least as far as \(\dfrac{6}{2} + \dfrac{8\sqrt{3}}{2\sqrt{3}}\) or \(\dfrac{6}{2} + \dfrac{8\sqrt{3}\sqrt{3}}{6}\) or \(\dfrac{6}{2} + \dfrac{24}{6}\)
25 Show that \(\quad \dfrac{4\sin 30^\circ - \tan 45^\circ}{2\cos 30^\circ} \quad\) can be written as \(\tan x\), where \(x\) is an acute angle. [4 marks]
Mark scheme
Answer
Mark
Comments
\(\sin 30 = \dfrac{1}{2}\) or \(\tan 45 = 1\) or \(\cos 30 = \dfrac{\sqrt{3}}{2}\)
M1
oe eg \(\tan 45 = \dfrac{\sqrt{2}}{\sqrt{2}}\) or \(4\sin 30 = 2\) or \(2\cos 30 = \sqrt{3}\) implied by position in the expression may be seen in a table
substitution of all three correct values
M1dep
eg \(\dfrac{4 \times \frac{1}{2} - 1}{2 \times \frac{\sqrt{3}}{2}}\) or \(\dfrac{2 - 1}{2 \times \frac{\sqrt{3}}{2}}\) or \(\dfrac{2 - 1}{\sqrt{3}}\)
\(\dfrac{1}{\sqrt{3}}\) or \(\dfrac{\sqrt{3}}{3}\)
M1dep
\(\left(\dfrac{1}{\sqrt{3}}\right.\) or \(\left.\dfrac{\sqrt{3}}{3} =\right)\ \tan 30\) or \(x = 30\) with full working seen for M3
A1
Additional guidance
Allow \(\sqrt{1}\) for 1 throughout
Reference to 30° being an acute angle is not required
29 Show that the value of \(\quad 5\sin 30^\circ \times \cos 30^\circ \times 8\tan 30^\circ \quad\) is an integer. [4 marks]
Mark scheme
Answer
Mark
Comments
Alternative method 1
\((\sin 30^\circ =)\ \dfrac{1}{2}\) or \((\cos 30^\circ =)\ \dfrac{\sqrt{3}}{2}\) or \((\tan 30^\circ =)\ \dfrac{1}{\sqrt{3}}\) or \(\dfrac{\sqrt{3}}{3}\) or \(\left(\dfrac{1/2}{\sqrt{3}/2}\right)\)
M1
may be seen beside question
\(5\left(\dfrac{1}{2}\right) \times \dfrac{\sqrt{3}}{2} \times 8\left(\dfrac{1}{\sqrt{3}}\right)\) or \(5\left(\dfrac{1}{2}\right) \times \dfrac{\sqrt{3}}{2} \times 8\left(\dfrac{1/2}{\sqrt{3}/2}\right)\) or \(\dfrac{5}{2} \times \dfrac{\sqrt{3}}{2} \times \dfrac{8\sqrt{3}}{3}\)
M1dep
oe multiplication string with all correct values
\(\dfrac{40\sqrt{3}}{4\sqrt{3}}\) or \(\dfrac{40\sqrt{3}\sqrt{3}}{12}\)
M1dep
oe single fraction with roots rationalised or able to be cancelled
10 from correct working
A1
Alternative method 2: substituting \(\dfrac{\sin}{\cos}\) for tan and cancelling
Allow \(\dfrac{\sqrt{3}}{2} \times \sqrt{3} + \dfrac{1}{2}\) given as \(\dfrac{\sqrt{3}}{2} \times \sqrt{3}\), followed by their \(\dfrac{3}{2} + \dfrac{1}{2}\)
Give your answer in the form \(\qquad \dfrac{\sqrt{a} - \sqrt{b}}{c} \qquad\) where \(a\), \(b\) and \(c\) are integers. [4 marks]
Mark scheme
Answer
Mark
Comments
\(\sin 45 = \dfrac{\sqrt{2}}{2}\) or \(\dfrac{1}{\sqrt{2}}\) or \(\tan 45 = 1\) or \(\dfrac{1}{1}\) or \(\tan 60 = \sqrt{3}\) or \(\dfrac{\sqrt{3}}{1}\)
B1
oe stated or in correct place in expression or implied by multiplier of 2 or 4
\(\sin 45 = \dfrac{\sqrt{2}}{2}\) or \(\dfrac{1}{\sqrt{2}}\) and \(\tan 45 = 1\) or \(\dfrac{1}{1}\) and \(\tan 60 = \sqrt{3}\) or \(\dfrac{\sqrt{3}}{1}\)
B1
oe stated or in correct place in expression or implied by multiplier of 2 or 4 eg \(\;\dfrac{2 \times \dfrac{1}{\sqrt{2}} - 1}{4 \times \dfrac{\sqrt{3}}{1}}\)
oe rationalisation of their denominator eg \(\;\dfrac{\dfrac{2}{\sqrt{2}} - 1}{4\sqrt{3}} \times \dfrac{4\sqrt{3}}{4\sqrt{3}}\)
\(\dfrac{\sqrt{6} - \sqrt{3}}{12}\)
A1
oe in the form \(\dfrac{\sqrt{6a^2} - \sqrt{3a^2}}{12a}\) where \(a\) is a positive integer eg \(\;\dfrac{\sqrt{24} - \sqrt{12}}{24}\) (when \(a = 2\))
Additional guidance
\(\dfrac{2 \times \dfrac{1}{\sqrt{2}} - 1}{4\sqrt{3}}\) or \(\dfrac{\sqrt{2} - 1}{4\sqrt{3}}\) or \(\dfrac{\sqrt{2} - 1}{\sqrt{48}}\)
B1B1
\(\dfrac{\sqrt{48}(\sqrt{2} - 1)}{\sqrt{48}\sqrt{48}}\) or \(\dfrac{\sqrt{48}(\sqrt{2} - 1)}{48}\)
B1B1M1
\(\dfrac{\sqrt{96} - \sqrt{48}}{48}\)
B1B1M1A1
B1B1 awarded, incorrect simplification, then correct method to rationalise
16 Work out the exact value of \(x\) in this triangle. [4]
Not to scale
Mark scheme
Answer
Marks
Part marks and guidance
\(\sqrt{31}\) final answer
4
B3 for answer 31 nfww
OR
B1 for \(\cos 30 = \frac{\sqrt{3}}{2}\)
and
M2 for \(x^2 = (6\sqrt{3})^2 + 7^2 - 2 \times 6\sqrt{3} \times 7\cos 30\) or better or M1 for other correct arrangements of cosine rule where \(x\) or \(x^2\) are not the subject
Do not accept work in decimals rounded to answers of \(\sqrt{31}\) or 31
Award if seen as clear statement of fact or in use; once seen condone replacement by 0.866… or 0.87 in subsequent work Condone missing brackets Condone use of 10.39… or 10.4 and 0.866… or 0.87 in M2 and M1
where \(x\) is ½ AB M1 for any correct implicit method for finding AB or ½ AB
B1 for \(\cos 30 = \frac{\sqrt{3}}{2}\) soi
A1 for \(12\sqrt{3}\)
In this method and other methods used, B1 is awarded for the correct trig value[s] associated with their method for find [½]AB, even if their method is incorrect, not just seen in a table of trig values unless selected
Award maximum of 6 marks if answer incorrect
If 0, 1 or 2, scored instead award SC3 for answer \(12\sqrt{3} + 16\pi\) If 0 or 1 scored, instead award SC2 for \(12\sqrt{3}\) or \(16\pi\) in answer
SEE AG
Additional guidance: Question 20
The length AB or \(\frac{1}{2}\) AB (\(12\sqrt{3}\) oe or \(6\sqrt{3}\) oe may be seen unsimplified e.g. \(2\sqrt{108}\) or \(\sqrt{108}\)) can be obtained by a number of different methods. M2 is for the explicit method leading to AB or \(\frac{1}{2}\)AB and examples of this are in the guidance column of the scheme
M1 is for a correct implicit method
The B mark is awarded for a correct trig value[s] for their chosen method
Implicit methods may include
\(\text{AB}^2 + (12\sin 30)^2 = 12^2\) oe or better
(a) Show that the area of the sector ACD is \(\frac{8}{3}\pi\) m2. [6]
(b) Work out the total area of the shape ABCD.
Give your answer in the form \(\left(\dfrac{a\sqrt{k}}{b} + \dfrac{8}{3}\pi\right)\) m2. [3]
Mark scheme (a)
Answer
Marks
Part marks and guidance
[\(AC =\)] \(\dfrac{4}{\cos 30}\) oe
M2
M1 for \(\frac{4}{AC} = \cos 30\) oe or for \(\frac{\sin 60}{4} = \frac{\sin 90}{AC}\) oe
Accept any variable for AC provided not incorrect length Accept longer methods using 4 tan 30 to find BC then Pythagoras’ or sine rule M2 for AC explicit
M1 for \(\frac{1}{2} \times 4 \times \frac{8}{\sqrt{3}} \times \sin 30\) FT their AC from (a) or for \(\frac{1}{2} \times 4 \times 4 \times \tan 30\) B1 for \(\sin 30 = \frac{1}{2}\) oe or for \(\tan 30 = \frac{\sqrt{3}}{3}\) oe
Accept e.g. \(\frac{16\sqrt{3}}{6} + \frac{8}{3}\pi\) for 3 marks
13 The diagram shows a triangle, ABC, with perpendicular height BD.
Not to scale
BC = 12 cm, angle BCD = 30° and angle BAD = 45°.
(a) Work out the length of BD. [3]
(b) Work out the exact length of AB. Give your answer in its simplest form. [3]
Mark scheme (a)
Answer
Marks
Part marks and guidance
6
3
M1 for sin 30 = \(\frac{BD}{12}\) oe B1 for sin 30 = 0.5 oe soi
Accept e.g. sin 30 = \(\frac{\sqrt{1}}{2}\) Do not allow B1 if contradicted
Mark scheme (b)
Answer
Marks
Part marks and guidance
\(6\sqrt{2}\) or \(\frac{12}{\sqrt{2}}\) cao
3
B2 for \(\sqrt{72}\) or better
OR M1 for \(\frac{their(a)}{\sin 45}\) [= \(AB\)] oe or 2(their (a))\(^2\) oe or \(\frac{12 \times \sin 30}{\sin 45}\) [= \(AB\)]
B1 for sin 45 = \(\frac{\sqrt{2}}{2}\) or \(\frac{1}{\sqrt{2}}\) oe soi
For M1, accept \(\frac{their(a)}{\cos 45}\) [= \(AB\)] oe For M1 , accept e.g. \(\frac{their(a) \times \sin 90}{\sin 45}\) [= \(AB\)] M1 implied by e.g. 72
For B1 accept cos 45 = \(\frac{\sqrt{2}}{2}\) or \(\frac{1}{\sqrt{2}}\) oe Do not allow B1 if contradicted
B2FT for final answer \(12\sqrt{3}\), 8, \(8\sqrt{3}\) or 6 if consistent with their (a) or M1 for \(24 \times \dfrac{1}{2}\) or \(24 \times\) their (a)
For 1 or 2 marks, isw attempts to simplify the surds
15 ABC is an equilateral triangle of side length 2 cm. M is the midpoint of AC.
Not to scale
Using this diagram, show that \(\tan 30^\circ = \dfrac{1}{\sqrt{3}}\). [4]
Mark scheme
Answer
Marks
Part marks and guidance
Correctly shows \(\tan 30^\circ = \frac{1}{\sqrt{3}}\) with supporting working
4
Using triangle MBC (mark similarly for use of triangle MBA):
B1 for MBC = 30° or MC = 1 [cm] soi by use in Pythagoras
M2 for [BM =] \(\sqrt{2^2 - 1^{[2]}}\) or \(\sqrt{4 - 1}\) [\(= \sqrt{3}\)] or for [BM2 =] \(2^2 - 1^{[2]}\) oe and \(\sqrt{3}\)
or M1 for \(\text{BM}^2 + 1^{[2]} = 2^2\) oe OR B1 for MCB = 60° or MC = 1 [cm] soi by use in cos rule
M2 for \(\sqrt{2^2 + 1^{[2]} - 2 \times 2 \times 1 \times \cos 60}\) and \(\cos 60 = \frac{1}{2}\) soi [\(= \sqrt{3}\)] or M1 for \(2^2 + 1^{[2]} - 2 \times 2 \times 1 \times \cos 60\) OR B1 for MCB = 60° soi by use in sine ratio or sine rule M2 for [\(x\) = ] 2sin 60 oe and \(\sin 60 = \frac{\sqrt{3}}{2}\) soi [\(= \sqrt{3}\)] or M1 for \(\frac{\sin 60}{x} = \frac{\sin 90}{2}\) oe AND A1dep for MBC = 30° stated/on diagram and \(\tan 30^\circ = \frac{1}{\sqrt{3}}\) and with no errors seen leading to the answer
If 0 or 1 scored, SC2 for \(\dfrac{\sin 30}{\cos 30} = \dfrac{\frac{1}{2}}{\frac{\sqrt{3}}{2}}\) and \(\tan 30 = \frac{1}{\sqrt{3}}\) May be on diagram
For M2 must show the subtraction, do not allow \(\text{BM}^2 + 1^{[2]} = 2^2\) and then \(\sqrt{3}\), this gets M1 only
(b) ADB and BCD are right-angled triangles. BC = CD. AD = \(10\sqrt{6}\) mm. Angle BAD = 30°.
\(\tan 30^\circ = \dfrac{1}{\sqrt{3}}\)
Not to scale
Work out the length of BC. [6]
Mark scheme (a)
Answer
Marks
Part marks and guidance
\(\frac{1}{\sqrt{2}}\) or \(\frac{\sqrt{2}}{2}\) final answer
1
Mark scheme (b)
Answer
Marks
Part marks and guidance
10 nfww
6
B3 for BD = \(10\sqrt{2}\) oe or M2 for \(10\sqrt{6} \times \tan 30\) oe or M1 for \(\frac{BD}{10\sqrt{6}} = \tan 30\) oe AND M2 for BC = \(\sqrt{\frac{\textit{their}\ BD^2}{2}}\) oe or their BD × their sin 45 oe or M1 for BC2 + CD2 = (their BD)2 or for \(\frac{BC}{\textit{their}\ BD} = \textit{their}\ \sin 45\)
Allow use of other variables for BC and CD (possibly different)
16 Sketch the graph of \(y = -\sin x\) for \(0^\circ \leqslant x \leqslant 360^\circ\).
[3]
Mark scheme
Answer
Marks
Part marks and guidance
Correct sketch of \(y = -\sin x\)
3
There must be at least one cycle to gain any marks.
B1 for a positive or negative sine curve shape starting at (0, 0) and B1 for maximums at (…, 1) and minimum at (…, –1) and B1 for maximum only at (270, …) and minimum only at (90, …)
e.g. B1B1B0 for \(y = \sin x\) drawn B0B1B0 for \(y = \pm\cos x\) drawn B1B1B0 for \(y = \sin 2x\) drawn
Before using overlay, check the x-axis line All maximums and minimums within the horizontal zones on overlay Maximum and minimum within the vertical zones on overlay
or M1 for \(\sin 60 = \dfrac{\sqrt{3}}{2}\) or \(\cos 30 = \dfrac{\sqrt{3}}{2}\)
To award 6 marks, there must be no errors seen
Beware circular methods using \(3\sqrt{3}\) leading to 60, this can only score M1 maximum for \(\sin 60 = \dfrac{\sqrt{3}}{2}\) but ignore circular methods if alongside a correct method
13 In the diagram, ABC is a right-angled triangle. P is a point on AB. BC = 40 m, AP = 20 m and angle ABC = 30°.
Not to scale
(a) Show that AC = 20 m. [3]
(b) Find the length of PB. Give your answer in the form \(a(\sqrt{3} - b)\), where \(a\) and \(b\) are integers. [5]
Mark scheme (a)
Answer
Marks
Part marks and guidance
AC = 40sin30
M2
M1 for \(\dfrac{\text{AC}}{40} = \sin 30\) oe
20 and evidence that sin 30 = 0.5
A1
If 0 scored, B1 for sin 30 = 0.5 oe
Mark scheme (b)
Answer
Marks
Part marks and guidance
\(20(\sqrt{3} - 1)\)
5
B4 for \(20\sqrt{3} - 20\) or \(\sqrt{1200} - 20\) or B3 for \(\sqrt{1200}\) or \(\dfrac{40\sqrt{3}}{2}\) or M2 for 40cos30 oe or M1 for \(\cos 30 = \dfrac{\text{AB}}{40}\) oe
Other methods are possible e.g. Pythag e.g. M2 for [AB =] \(\sqrt{40^2 - 20^2}\) e.g. M1 for AB² + 20² = 40²