waecmaths question:
The perimeter of a sector of a circle 4cm is $(\pi +8)cm$ . Calculate the angle of the sector
Option A:
45o
Option B:
60o
Option C:
75o
Option D:
90o
waecmaths solution:
$\begin{align} & perimeter=\frac{\theta }{{{360}^{\circ }}}\times 2\pi r+2r=\pi +8 \\ & \left( \frac{\theta }{{{360}^{\circ }}}\times 2\pi \times 4 \right)+(2\times 4)=\pi +8 \\ & \frac{\theta }{{{360}^{\circ }}}\times 2\pi \times 4=\pi \\ & \theta =\frac{{{360}^{\circ }}}{8}={{45}^{\circ }} \\\end{align}$
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