JAMB - Mathematics (1994 - No. 27)
Calculate the perimeter, in cm, of a sector of a circle of radius 8cm and angle 45o
2\(\pi\)
8 + 2\(\pi\)
16 + 2\(\pi\)
16 + 16\(\pi\)
Explanation
Perimeter = OP + OQ + PQ
= 8 + 8 + PQ
length PQ = \(\frac{\theta}{360 \times 2\pi r}\)
= \(\frac{45}{360}\) x 2 x \(\pi\) x 8
= 2\(\pi\)
Perimeter of sector 2r + L
Where l = length of arc and r = radius
∴ P = 2(8) + 2\(\pi\)
= 16 + 2\(\pi\)
= 8 + 8 + PQ
length PQ = \(\frac{\theta}{360 \times 2\pi r}\)
= \(\frac{45}{360}\) x 2 x \(\pi\) x 8
= 2\(\pi\)
Perimeter of sector 2r + L
Where l = length of arc and r = radius
∴ P = 2(8) + 2\(\pi\)
= 16 + 2\(\pi\)
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