JAMB - Mathematics (1979 - No. 3)
If the value of \(\pi\) is taken to be \(\frac{22}{7}\), the area of a semi-circle of diameter 42m is
5544m2
1386m2
132m2
264m2
693m2
Explanation
\(\pi\) = \(\frac{22}{7}\), Diameter D = 42m
Area of a circle = \(\frac{\pi D^2}{4}\) when a diameter is given
area of a semicircle \(\frac{\pi D^2}{4}\) x \(\frac{1}{2}\)
= \(\frac{22}{7}\) x \(\frac{5541.7694}{4}\) x \(\frac{1}{2}\)
= \(\frac{11}{7} \times 441\)
= 693m\(^{2}\)
Area of a circle = \(\frac{\pi D^2}{4}\) when a diameter is given
area of a semicircle \(\frac{\pi D^2}{4}\) x \(\frac{1}{2}\)
= \(\frac{22}{7}\) x \(\frac{5541.7694}{4}\) x \(\frac{1}{2}\)
= \(\frac{11}{7} \times 441\)
= 693m\(^{2}\)
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