A(r)=pi r^2 to compute a(8)
A(8)=pi (8)^2. The area is 64 pi units squared. Unless I misunderstood the question.
I used to know the answer but I've misplaced my slide-rule.
Is this in hieroglyphics?
Area of a circle = pi*r^2. A(8) is what the second coordinate value is in a Cartesian pair at 8. A(r) = is pi*r^2 reads "the function at r is the area of a circle. Something must have been miss typed - the best you can analyze any value of r will churn out 0. Try re-typing it again.
A(8)= pi (8)^2A(8)=64 pi