A solid cylinder of radius 3cm has a total surface area of 36\(\pi\)cm2. Find its height
- 2cm
-
3cm
- 4cm
- 5cm
- 6cm
The correct answer is: B
Explanation
Area 2\(\pi\)r2 + 2 \(\pi\)r(r + h)
= 2\(\pi\)r(r + h)
36\(\pi\) = 6\(\pi\)(r + h)
36\(\pi\) = 6\(\pi\)(3 + h)
36\(\pi\) = 18\(\pi\) + 6\(\pi\)h
36\(\pi\) - 18\(\pi\) = 6\(\pi\)h
Divide both side by 6\(\pi\)
h = 3cm