Question

A circle has centre (0, 0) and it passes through the point (5, -3)

Find the radius of the circle, in surd form.

Answer 1

radius =
`√(34)`

Explanation:

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

Use the distance formula to calculate r

r = √ (x₂ - x₁ )² + (y₂ - y₁ )²

with (x₁, y₁ ) = (0, 0) and (x₂, y₂ ) = (5, - 3)

r =
`√((5-0)^2+(- 3-0)^2)`

=
`√(5^2+(-3)^2)`

=
`√(25+9)`

=
`√(34)`