Edexcel C2 2013 June — Question 8 11 marks

Exam BoardEdexcel
ModuleC2 (Core Mathematics 2)
Year2013
SessionJune
Marks11
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicStandard trigonometric equations
TypeMultiple independent equations — includes show/prove component
DifficultyStandard +0.3 This is a standard C2 trigonometric equation question with routine techniques: part (i) requires basic inverse tan with period adjustment, part (ii)(a) is a guided algebraic manipulation using tan=sin/cos and Pythagorean identity, and part (ii)(b) solves a quadratic in cos θ. All steps are well-practiced textbook methods with no novel insight required, making it slightly easier than average.
Spec1.05j Trigonometric identities: tan=sin/cos and sin^2+cos^2=11.05k Further identities: sec^2=1+tan^2 and cosec^2=1+cot^21.05o Trigonometric equations: solve in given intervals

8. (i) Solve, for \(- 180 ^ { \circ } \leqslant x < 180 ^ { \circ }\), $$\tan \left( x - 40 ^ { \circ } \right) = 1.5$$ giving your answers to 1 decimal place.
(ii) (a) Show that the equation $$\sin \theta \tan \theta = 3 \cos \theta + 2$$ can be written in the form $$4 \cos ^ { 2 } \theta + 2 \cos \theta - 1 = 0$$ (b) Hence solve, for \(0 \leqslant \theta < 360 ^ { \circ }\), $$\sin \theta \tan \theta = 3 \cos \theta + 2$$ showing each stage of your working.

8. (i) Solve, for $- 180 ^ { \circ } \leqslant x < 180 ^ { \circ }$,

$$\tan \left( x - 40 ^ { \circ } \right) = 1.5$$

giving your answers to 1 decimal place.\\
(ii) (a) Show that the equation

$$\sin \theta \tan \theta = 3 \cos \theta + 2$$

can be written in the form

$$4 \cos ^ { 2 } \theta + 2 \cos \theta - 1 = 0$$

(b) Hence solve, for $0 \leqslant \theta < 360 ^ { \circ }$,

$$\sin \theta \tan \theta = 3 \cos \theta + 2$$

showing each stage of your working.\\

\hfill \mbox{\textit{Edexcel C2 2013 Q8 [11]}}