Q: The area of a circle is 16(pi) cm squared. What is the diameter of the circle?
First we need to know the area formula for a circle… This is:
A = pi*r^2 [r is the radius]
Since the area is given to us, we can plug that in to the formula to get:
16*pi = pi*r^2
The only variable is r, so we can use algebra to solve for r like so:
Divide both sides by pi (which makes the pi’s cancel out):
16*pi /pi = pi*r^2 /pi
16 = r^2
Now, take the square root of both sides to solve for r:
sqrt(16) = r
4 = r
So, the radius of the circle is 4. The diameter is 2*radius… So, the diameter is 8 cm.