WAEC - Mathematics (2017 - No. 16)

If the total surface area of a solid hemisphere is equal to its volume, find the radius

3.0cm

4.5cm

5.0cm

9.0cm

T.S.A of hemisphere = 3\(\pi r^2\)

vol of hemisphere = \(\frac{2}{3} \pi r^3\)

3\(\pi r^2\) = \(\frac{2}{3} \pi r^3\)

3 = \(\frac{2}{3}r\)

9 = 2r

r = \(\frac{9}{2}\)

r = 4.5cm