WAEC - Mathematics (1989 - No. 35)
The angle of a sector of a circle of diameter 8cm is 135°. Find the area of the sector [Take \(\pi\) = 22/7].
\(9\frac{3}{7}cm^2\)
\(12\frac{4}{7}cm^2\)
\(18\frac{6}{7}cm^2\)
\(25\frac{1}{7}cm^2\)
คำอธิบาย
Area of a sector
\(\frac{θ}{360°} * πr^2\)
= \(\frac{135}{360} * 3.142 * 4 * 4\)
= \(18\frac{6}{7}cm^2\)