Question 1044022
Q: What is the expression for the area of the circle which has a circumference of C? Express your answers as a rational expression in terms of C and pi. 
Solution:
{{{C = 2*pi*r}}}
So {{{r = C/(2*pi)}}}
The area of the circle is equal to
{{{A = pi*r^2}}}
{{{A = pi*(C/(2*pi))^2 }}}
{{{highlight(A = C^2/(4*pi)) }}}
Q: in China, spheres are used to exercise a person's hands. if the diameter of a sphere is 2 inches how many square inches are in its surface area express your answer in terms of pi.
sOLUTION: If diameter = 2 inches, then radius=  (2 inches)/2 = 1 inch
The area of the circle is equal to
{{{A = pi*r^2}}}
{{{A = pi*(1)^2}}}
A = {{{highlight( pi )}}}sq inch