A Level

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

Problem

Evaluate E=(sin⁡70∘cos⁡25∘−cos⁡70∘sin⁡25∘)+(cos⁡70∘cos⁡25∘+sin⁡70∘sin⁡25∘)\displaystyle E=\bigl(\sin70^{\circ}\cos25^{\circ}-\cos70^{\circ}\sin25^{\circ}\bigr)+\bigl(\cos70^{\circ}\cos25^{\circ}+\sin70^{\circ}\sin25^{\circ}\bigr). (a) 3\sqrt3 (b) 2\sqrt2 (c) 1 (d) 22\dfrac{\sqrt2}{2}

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