What is the function for radius? Equation is a=pieradiussquared

Question

I need help on this problem for a math quiz!! Please help. I am lost! any help I can get would be perfect thanks!

Answer 1

A diameter is a straight segment that passes through the center of a circle.

 

a radius is half a diameter. d=2r

 

A=area, pi=pi or 22/7 or 3.14, r=radius

The formula for the area of a circle is pi*r^2...that is A=pi*r*r

in order to find r using the formula..divide both sides by pi

 

A/pi=pi*r*r/pi

A/pi=r*r

to find r, find square root of both sides

r=square root of A/pi

 

 

 

Answer 2

We need to take

 

a = pi*r²

 

and solve for r. First, we need to move pi to the other side:

 

r^{2 = a/pi}

 

Then we take the square root of both sides to get:

 

r = ±sqrt(a/pi)

 

Since radius is usually expressed as a positive number, you would just use sqrt(a/pi).