Question

Type the correct answer in each box. A circle is centered at the point (-7, -1) and passes through the point (8, 7). The radius of the circle is units. The point (-15, ) lies on this circle.

Answer 1

r = 17 units

Explanation:

The radius is the distance from the centre (- 7, - 1) to the point on the circle

(8, 7)

Use the distance formula to calculate the radius (r)

r = √ (x₂ - x₁ )² + (y₂ - y₁ )²

with (x₁, y₁ ) = (- 7, - 1) and (x₂, y₂ ) = (8, 7)

r =
`√((8+7)^2+(7+1)^2)`

=
`√(15^2+8^2)`

=
`√(225+64)`

=
`√(289)` = 17 units