Question

What is the radius of the circle?

Answer 1

`r=4\ units`

Explanation:

we know that

The radius of the circle is equal to the distance from the center of the circle to any point on the circle

the formula to calculate the distance between two points is equal to

`d=\sqrt{(y2-y1)^(2)+(x2-x1)^(2)}`

we have that the center of the circle is the point (-1,1)

take another point that is on the circle

I take the point (-1,5)

substitute in the formula

`r=\sqrt{(5-1)^(2)+(-1+1)^(2)}`

`r=\sqrt{(4)^(2)+(0)^(2)}`

`r=4\ units`