Question

Find an equation of the circle having the given center and radius.
Center ( - 1, 1), radius 7

Answer 1

(x+1)^2+(y-1)^2=49

Explanation:

The standard equation of a circle is

(x-h)^2+(y-k)^2=r^2

where the center is (h,k) and r is the radius

so h=-1 and k=1 in this case

so then (x- -1)^2+(y-1)^2=7^2

(x+1)^2+(y-1)^2=49

Answer 2

(x+1)^2 + (y+1)^2 = 49

Explanation:

We can write the equation of a circle as

(x-h)^2 + (y-k)^2 = r^2

where (h,k) is the center and r is the radius

(x- -1)^2 + (y- -1)^2 = 7^2

Simplifying

(x+1)^2 + (y+1)^2 = 49