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
คำอธิบาย
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