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.
Reset
Next

Answer 1

17 units

Explanation:

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

To calculate r use the distance formula

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