Evaluate the following: 78^ 18^ - 78^ 18^ - Vidyadip

Question

Evaluate the following: $\sin78^\circ\cos18^\circ-\cos78^\circ\sin18^\circ$

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Answer

$=\sin(78^\circ-18^\circ)$ $[\sin(\text{A-B})=\sin\text{A}\cos\text{B}-\cos\text{A}\sin\text{B}]$ $=\sin60^\circ$ $=\frac{\sqrt{3}}{2}$

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