XYZ is a circle enter o and a radius 7cm Find t... - JAMB Mathematics 2003 Question
XYZ is a circle enter o and a radius 7cm. Find the area of the shaded region. θ = 45 x 2 = 90
A
84cm2
B
77cm2
C
38cm2
D
14cm2
correct option: d
θ = 45 x 2 (∠ at center twice ∠ at θ)
θ = 90
Area of sector = θ/360 x πr2
= 90/360 x 22/7 x 7 x 7
= 77/2cm2
Area of triangle = 1/2 ab sin θ
= 1/2 x 7 x 7 sin 90
= 1/2 x 7 x 7 x 1
= 49/2
Area of shaded region = 77/2 - 49/2
= 28/2
= 14cm2
θ = 90
Area of sector = θ/360 x πr2
= 90/360 x 22/7 x 7 x 7
= 77/2cm2
Area of triangle = 1/2 ab sin θ
= 1/2 x 7 x 7 sin 90
= 1/2 x 7 x 7 x 1
= 49/2
Area of shaded region = 77/2 - 49/2
1 | 1 |
2 |
= 28/2
= 14cm2
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