Question

The center of Circle D is (0, 0). The circumference of the circle passes through Point E (-7, -4). Find the length of the radius of Circle D.

Answer 1

radius =
`√(65)`

Explanation:

The radius of the circle is the distance from the centre to a point on the circumference.

Calculate the radius using the distance formula

r = √(x₂ - x₁ )² + (y₂ - y₁ )²

with (x₁, y₁ ) = (0, 0) and (x₂, y₂ ) = (- 7, - 4)

r =
`√((-7-0)^2+(-4-0)^2)` =
`√(49+16)` =
`√(65)`