Question

Circle A has a diameter of 9 inches, a circumference of 28.26 inches, and an area of 63.585 square inches. The diameter of circle B is 5 inches, the circumference is 15.70 inches, and the area is 19.625 square inches..
Part A: Using the formula for circumference, solve for the value of pi for each circle.

Part B: Use the formula for area and solve for the value of pi for each circle.


Part C: What observation can you make about the value of pi for circles A and B?

Answer 1

A) The equation for circumference is C=2piR. So Filling in for circle A we have 28.26=2*pi*4.5 so we want to isolate pi which I'm gonna call x for it's easier for me xD. So we're gonna start by dividing 4.5 from each side which is gonna leave us with 6.28=2*x which gives you x(pi)= 3.14. For circle B we have 15.70=2*x*2.5 isolate x by first dividing 2.5 which leaves us again with 6.28=2x and x= 3.14. 
B) The equation for area is A=piR^2. So again for circle A we have 63.585=x9^2. This one is harder but also are you sure that the area is 63.585 it's supposed to be 254.469 (We'll come back to this)
C) The observation you can make about the value of pi for circles A and B is that it stays consistent at 3.14