CAIE A Level Mathematics 9709 · Trigonometry (A2)

Trigonometry (A2): calculation question

3 marksStandard

Given that $\sin\theta = \frac35$ and that $\theta$ is obtuse (so $\cos\theta$ is negative), find the following exact values.

(a)
$\sin 2\theta$
[2]
(b)
$\cos 2\theta$
[1]

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