JAMB - Mathematics (2021 - No. 17)
The angle of a sector of a circle, radius 10.5cm, is 48°, Calculate the perimeter of the sector
8.8cm
25.4cm
25.6cm
29.8cm
Explanation
Length of Arc AB = \(\frac{\theta}{360}\) 2\(\pi\)r
= \(\frac{48}{360}\) x 2\(\frac{22}{7}\) x \(\frac{21}{2}\)
= \(\frac{4 \times 22 \times \times 3}{30}\) \(\frac{88}{10}\) = 8.8cm
Perimeter = 8.8 + 2r
= 8.8 + 2(10.5)
= 8.8 + 21
= 29.8cm
= \(\frac{48}{360}\) x 2\(\frac{22}{7}\) x \(\frac{21}{2}\)
= \(\frac{4 \times 22 \times \times 3}{30}\) \(\frac{88}{10}\) = 8.8cm
Perimeter = 8.8 + 2r
= 8.8 + 2(10.5)
= 8.8 + 21
= 29.8cm
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