Question

Why is the answer B? Plz explain.

Answer 1

Step One

Develop a formula for the perimeter.

Argument

What you see is a semicircle going upwards and another one going downwards. Two semicircles =1 circle.

The "perimeter" [Circumfrence] of a whole circle = 2*pi*r

We are told that whatever you call this the perimeter is 8pi + 16

Step Two

Set up the equation

8pi + 16 = 2*pi*r + 4r Including the line connecting these two.

Step Three

Take out the common factors on the left and right.

8(pi + 2) = 2r(pi + 2) Divide both sides by pi + 2

8 = 2r Divide by 2

4 = r

Sorry. I didn't know the meaning of perimeter. Mathmate is perfectly correct.