 Shalune Dec 9, 2020

# Plzzzzzzzzzzzzzfind perimeter and area of semicircle with radius of 8cm​ The time for answering the question is over

8

centimetres. Recall that the centre angle in a circle is always

360

˚

. However, a semi-circle is a circle cut in half. Hence, the centre angle for the semi-circle is cut in half, or has a measure of

180

˚

.

Here's a diagram of what's going on.

enter image source here

Before applying the formula, let's convert

180

˚

180

˚

1

×

π

180

˚

=

π

We will now use the formula to determine the area of this semi-circle.

A

=

1

2

×

π

×

8

2

A

=

1

2

×

π

×

64

A

=

32

π

c

m

2

We can confirm this using the formula for area of a semi-circle,

A

=

r

2

π

2

.

A

=

8

2

π

2

A

=

32

π

c

m

2

Same, so both formulae work.

Here are a few problems for you practice.

Practice exercises:

Determine the area of the following semi-circles.

a) The semi-circle contained inside a circle of radius

5

inches.

b) The semi-circle contained inside a circle of diameter

22

feet.

c) The semi-circle contained inside a circle of circumference

18

meters.

Hopefully this helps, and good luck!

191 Maksim
Dec 9, 2020 