Question

1. Which is an equation of a circle with center (2, -10) and radius 3? a-(x - 2)2 + (y + 10)2 = 3 b- (x - 2)2 + (y + 10)2 = 9 c- (x + 10)2 + (y - 2)2 = 9 d- (x + 2)2 + (y - 10)2 = 3

Answer 1

B

Explanation:

(x-2)^2+(y+10)^2 = 9

as 3 is the radius we always take its square which is 9 so options A and D are not correct.

The equation in general form is like this : (x-a)^2 + (y-b)^2 = r^2

hence if x is 2 then equation will be like

( x - 2 )^2+(y+10)^2 = 9

if y is -10 then equation will be

(x-2)^2+(y+10)^2 = 9