Question

What is the equation of the circle graphed below? Use the caret ( ^ ) to enter any exponents; for example, write x2 as x^2.

Answer 1

Equation of a circle in standard form:
(x-h)²+(y-k)²=r²
r=radius
(h,k) is the center.

In this case:
(h,k) =(0,0)   (h=0,k=0 )
r=4

Therefore:
(x-0)²+(y-0)²=4²
x²+y²=16

Answer: x²+y²=16