Question

the radius of a circle is 10 centimeters. what is the area of a sector bounded by a 90° arc? give the exact answer in simplest form

Answer 1

If the radius of the circle is 10 centimeters, the formula to get the area would be $\pi r^2$, and that would give us the area of $100 \pi$ square centimeters. $\frac{360}{90}$ would give us 4, so $\frac{100}{4}$ would give us the answer of 25 square centimeters. 

I hope this helped!!! ^^

Answer 2

I hope this isn't too late! You can find the answer to this by first finding the area of the circle, A=πr². So since the radius is 10, we input that into the equation to get π100. Now, there is 360° in a circle and a sector of 90° is 1/4 of it. So to answer the question all you have to do is find 1/4 of the area of the circle. 

The answer is π25.

To solve the other questions on your assignment just think about how much the sector is of the full 360° of the circle, for example 180° is 1/2 of the circle or 270° is 3/4 of the circle, and multiply the fraction by the area of the circle.

Hope this helped, good luck! :)