Question

What is the best approximation for the perimeter of a semicircle with a diameter of 12 cm?

Use 3.14 to approximate pi.

A. 18.84 cm
B. 30.84 cm
C. 61.68 cm
D. 75.36 cm

PLEASE HELP!

Answer 1

To find the circumference of a circle, we use this formula: C = (2)(pi)(r)

We'll use 3.14 for pi. And the radius is one half of a diameter.

C = (2)(3.14)(6) = 37.68

Then because we want the perimeter of a semi-circle, we half it.
37.68 / 2 = 18.84

Answer 2

First, we know that the equation for permeter of a circle is C=2*pi*4 or C=2*3.14*r if you are using 3.14 for pi. Since this is a semicircle, we simply divide this equation by 2 and plug in our radius (radius id 6 because 12/2 =6)

So we are using C=3.14*r
C=3.14*6
So the perimeter equals 18.84 so A

Hope this helps!