waecmaths question:
If $\cos {{(x+25)}^{o}}=\sin {{45}^{o}}$, find the value of x
Option A:
20
Option B:
30
Option C:
45
Option D:
60
waecmaths solution:
$\begin{align} & \cos (x+{{25}^{\circ }})=\sin {{45}^{\circ }} \\ & \cos (x+{{25}^{\circ }})=\sin [90-(x+{{25}^{\circ }})]=sin{{45}^{\circ }} \\ & \sin ({{65}^{\circ }}-x)=sin{{45}^{\circ }} \\ & {{65}^{\circ }}-x={{45}^{\circ }} \\ & x={{20}^{\circ }} \\\end{align}$
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