Which of the following gives all solutions of x 20^ - x 20^ =0 in ?

MATHEMATICS · Single correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

Which of the following gives all solutions of cos⁡xcos⁡20∘−sin⁡xsin⁡20∘=0\cos x\cos 20^{\circ}-\sin x\sin 20^{\circ}=0 in 0∘≤x<360∘0^{\circ}\le x<360^{\circ}? (a) 20∘,  200∘20^{\circ},\;200^{\circ} (b) 110∘,  290∘110^{\circ},\;290^{\circ} (c) 70∘,  250∘70^{\circ},\;250^{\circ} (d) 160∘,  340∘160^{\circ},\;340^{\circ}

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