Questions: Help with Geometry ch.3.1 #36. We don’t understand how to get the last step in the answer. How does the 4 get under the “pie” and not also under the d square? Thanks

Answer from Dr. Callahan:

Take these steps

A = pi*r^2

and

r= d/2

Now substitute r from the second equation into the first to get

A = pi (d/2)^2 — so you are squaring both the d and the 2.

to get

A = pi * d^2 / 4