Geometry..help!

My teacher gave us an assignment having to do with circles and such..and Im a little confused. It talks about like

D= 45 m



But the teacher says to find the radius, and We dont know how because their isnt a radius so it should be something like

A= 45 x r x pi


how do u find the R in the problem if the problem only says D=45m?

R means radius, which is the distance from the center of a circle to its edge.

D is diameter, which is always twice the radius.

So, when given D=45, divide by 2, and you have 22.5, which is R.

and then: just for future reference, you can find the circumfrence or distance around the circle by multiplying PI x R squared.
I know you didn't ask for that, but it's better to know something you don't need than to not know something you need.

Not meaning to step on your toes, BlackTalon, but the circumference (sp?) is 2 x PI x R. Your formula, though correct, is for finding the area of a circle.