I started a new math class today and I'm stuck on a problem from my worksheet. I need help with these questions.

If the measure of an exterior angle drawn at vertex M of triangle LMN is x, then mangleL + mangleN is what?

What is the area of a circle with the circumference of 18pi centimeteres? Give your answer in terms of pi.

The exterior angle is equal to the sum of the other two interior angles.

C= PI*diameter= PI*radius*2
Area= PI*radius^2= PI (C/2PI)^2= C^2/4PI

check that.