Question

Which circles have an area of 36pift2?

Answer 1

Area=pi times radius^2
area=36pi
36pi=pi times radius^2
divide both sides by pi
36=radius^2
square root both sides
6=radius

2radius=diameter
2 times 6=12
radius=6
diamater=12

the answers area A and D
(if you know your radius and diameter, you would know that diameter is 2 times radius and you could eliminate 2 choices imedietly (B and C))