Question

the point 3,2 lies on a circle.what is the exact length of the radius of this circle if the center is located at (-1,-4)

Answer 1

You can use the distance formula to solve this.

Distance Formula:
$d = \sqrt{(X_2 -X_1)^2 + (Y_2 - Y_1)^2}$

I am going to use point (3,2) as point 1 and (-1,-4) as point 2
Insert the points into the formula
$d = \sqrt{(X_2 -X_1)^2 + (Y_2 - Y_1)^2}$
$d = \sqrt{((-1) - 3)^2 + ((-4) - 2)^2}$
Solve:
$d = \sqrt{((-1) - 3)^2 + ((-4) - 2)^2}$
$d = \sqrt{(-4)^2 + (-6)^2}$
$d = \sqrt{16 + 36}$
$d = \sqrt{52}$
$d = \sqrt{52} = \sqrt{4}\sqrt{13}$
$d = \sqrt{52} = 2 \sqrt{13}$
$d = 2 \sqrt{13}$
$radius = 2 \sqrt{13} = 7.2111$