Question

The diameter of a semicircle is 4 miles. What is the semicircle's radius?

Answer 1

2 miles

Explanation:

The diameter is twice the radius, or

d=2r

We know the diameter is 4, so we can substitute that in for d

4=2r

We want to find r, so we need to solve for it. To do that, we need to get r by itself. r is being multiplied by 2. To undo this, divide both sides by 2, since division is the opposite of multiplication

4/2=2r/2

The 2s on the right will cancel, and we are left with

2=r

So, the radius is 2 miles

Answer 2

2 miles

Explanation:

The diameter is the line segment that cuts through the center of the circle and has endpoints on the circle. The radius is simply half of the diameter: d = 2r

Here, the diameter is 4 miles, so plug this in:

d = 2r

4 = 2r

r = 4/2 = 2 miles

Hope this helps!