Question

Area of Partial Circles


EXPERTS I NEED HELP!!!!

Answer 1

The part of a circle that is in this problem is a semi-circle, which is exactly half of a circle.

That means you can do the area of a circle (pi * r^2) and half it to find the area of the semi-circle.

You've also been told to approximate pi with 3.14.

So first, work out the area of the rectangle (18 * 6 = 108)

Now, time for the semi-circle. The diameter of the semi-circle is the same as the length of the rectangle (6 cm), hence you can half it to find the radius (3 cm).

Now just do 3.14 * 3^2 (which is the same as 3.14 * 9) and then half it.

3.14 * 9 = 28.26

28.26 / 2 = 14.13.

Now add the areas together.

14.13 + 108 = 122.13 cm²

Answer 2

For partial circles, first imagine that there is an entire circle. To find the area of a cicle, you use the formula A=pi*r^2 or A=3.14*r^2. Then determine how much of a circl you have so you can alter the formula. Since you have a semicircle, or half a circle, simply divide the formula in half:

A=(3.14*r^2)/2

Then plug in your radius to find the area. So for this problem you do:
A=(3.14*3^2)/2
A=28.26/2
A=14.13 is the area of the semicircle

Then since the rectangle would be 108 (18*6)

The total area is 122.13 (14.13+108)

Hope this helps!