2D Area & Perimeter: WJEC GCSE Higher November 2020 Unit 2 Q2

Higher November 2020 Unit 2 Q2

WJECHigherCurrent spec7 marks2D Area & Perimeter Pythagoras

2. In this question, you will be assessed on the quality of your organisation, communication and accuracy in writing.

The diagram shows two right-angled triangles, joined together along a common side.
AB = 10·8 cm, BC = 14·4 cm and CD = 24 cm.

Diagram not drawn to scale

Calculate the area of triangle ACD.
You must show all your working. [5 + 2 OCW]

Mark scheme

Scheme	Marks	Comments
\((AC^2 =)\ 10{\cdot}8^2 + 14{\cdot}4^2\)	M1	Accept equivalent of using cos rule (as cos 90 = 0).
\(AC^2 = 324\) or \((AC =)\ \sqrt{324}\)	A1
(AC =) 18(cm)	A1	F.T. √’their 324’ provided M1 gained. Final answer of AC = 324 is M1A0A0.
(Area ACD =) \(\dfrac{24 \times 18}{2}\)	M1	FT ‘their stated AC’. (May be shown on the diagram) Accept equivalent of using ½ × 24 × 18 × sin 90 (as sin 90 = 1).
= 216 (cm²)	A1
Organisation and Communication	OC1	For OC1, candidates will be expected to: present their response in a structured way explain to the reader what they are doing at each step of their response lay out their explanation and working in a way that is clear and logical write a conclusion that draws together their results and explains what their answer means
Accuracy of writing	W1	For W1, candidates will be expected to: show all their working make few, if any, errors in spelling, punctuation and grammar use correct mathematical form in their working use appropriate terminology, units, etc.

Scheme	Marks	Comments
A correct and complete method (using two trigonometric relationships)	M2
AC = 18(cm)	A1