#1**+1 **

We suspect that it's the first one, so let's explore the possibility.

Let's try to figure it out logically. Okay, pi r squared is the area of an entire circle.

Now it might not be good to start with an angle like, oh, 77^{o} for instance. Hard to visualize.

Pick an angle that's obvious, easy to visualize. So, why don't we pick 180^{o} to start with.

We know that 180^{o} represents half a circle, and 180/360 = 1/2 so that works out good.

Try 90^{o} next. That's obviously a fourth of a circle, and 90/360 = 1/4 so I think we can be confident.

It's definitely the first one.

Guest Jan 30, 2020