WAEC - Mathematics (2019 - No. 21)

The total surface area of a solid cylinder 165cm\(^2\). Of the base diameter is 7cm, calculate its height. [Take \(\pi = \frac{22}{7}\)]
7.5 cm
4.5 cm
4.0 cm
2.0 cm

Explanation

165 = 2 x \(\frac{22}{7}\) x \(\frac{7}{2}\) x h + 2 x \(\frac{22}{7}\) x \(\frac{7}{2}\) x \(\frac{7}{2}\)

165 = 22h + 77 

\(\frac{22h}{22} = \frac{88}{22}\)

height = 4cm

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