Find the length of a radius of each circle. Match each of the equations with length of a radius to obtain a true statement.
-$r = 20$
A) $x ^ { 2 } + y ^ { 2 } = 3$
B) $x ^ { 2 } + y ^ { 2 } + 14 x + 6 y + 39 = 0$
C) $x ^ { 2 } + y ^ { 2 } - 12 x + 20 y + 101 = 0$
D) $x ^ { 2 } + y ^ { 2 } + 24 x - 32 y = 0$

Question

Find the length of a radius of each circle. Match each of the equations with length of a radius to obtain a true statement.
-$r = 20$ 
A) $x ^ { 2 } + y ^ { 2 } = 3$ 
B) $x ^ { 2 } + y ^ { 2 } + 14 x + 6 y + 39 = 0$ 
C) $x ^ { 2 } + y ^ { 2 } - 12 x + 20 y + 101 = 0$ 
D) $x ^ { 2 } + y ^ { 2 } + 24 x - 32 y = 0$

Quizplus · Accepted Answer

The equation of a circle is $(x - h)^2 + (y - k)^2 = r^2$. For D, completing the square gives $(x + 12)^2 + (y - 16)^2 = 20^2$, so the radius is 20.

Find the Length of a Radius of Each Circle r=20r = 20r=20

Find the Length of a Radius of Each Circle $r = 20$