Find the standard equation of the circle being described in each item.

Question

 With center at the origin, radius √11

Answer 1

Standard equation of the circle with the center at the origin is x²+y²=r²

r=√11

x²+y²=(√11)²

 

Answer:

x²+y²=11

Answer 2

The equation of a circle with radius (r) and center (h,k) is:

(x-h)² + (y-k)² = r²

 

If the center is at the origin, then (h,k) = (0,0)   h=0, k=0

the radius is √11, so r² = 11

Therefore, 

(x-0)² + (y-0)^{2 =} 11   so   x² + y² = 11 is the equation