1.  A right triangle with sides 3 cm, 4 cm and 5 cm is rotated the side of 3 cm to form a cone. The volume of the cone so formed is:
A. 12 cm3
B. 15 cm3
C. 16 cm3
D. 20 cm3

Answer: Option A

Explanation:

Clearly, we have r = 3 cm and h = 4 cm.

Volume = 1 r2h = 1 x x 32 x 4 cm3
3 3
                                  = 12 cm3.