A cirlcle in the standard (x,y) coordinate plane has its center at (-4,3) and a radius of 5 units.?

Question

Which of the following equations represents this circle?


A. (x-4)^2 + (y+3)^2 = square root of 5

B. (x+4)^2 + (y-3)^2 = 5

C. (x-4)^2 + (y+3)^2 = 5

D. (x+4)^2 + (y-3)^2 = 25

E. (x-4)^2 + (y+3)^2 = 25



so how do you do this?

Answer 1

There isn't a huge amount to memorize in math, but this is one, and it is in completely standard form.

If you have a circle centered at (a,b) with radius r, its equation is:
(x-a)² + (y-b)² = r²

That means D in this case.

Answer 2

(x+4)^2+(y-3)^2 =25 (D)