4MA0 Higher January 2012 Paper 4 Q18

EdexcelHigherOld spec3 marksAdvanced Trigonometry

Triangle with sides 4 cm, 6 cm and 8 cm; angle x degrees between the 4 cm and 6 cm sides

Diagram NOT accurately drawn

Calculate the value of \(x\).
Give your answer correct to 1 decimal place.

(3)

Mark scheme

Scheme	Marks
\((\cos x^\circ =) \dfrac{4^2 + 6^2 - 8^2}{2 \times 4 \times 6}\) or \(8^2 = 4^2 + 6^2 - 2 \times 4 \times 6 \cos x^\circ\)	M1
\((\cos x^\circ =)\ -0.25\) oe	A1
104.5	A1
	(Total 3 marks)

Notes

M1: for correct substitution in Cosine Rule

A1: for value rounding to 104.5 (104.4775…)

Apart from Questions 3, 13(b) and 17(f) (where the mark scheme states otherwise), the correct answer, unless clearly obtained by an incorrect method, should be taken to imply a correct method.