Question

The equation of a circle is x2 + y2 = 42.25
find the radius of the circle

Answer 1

The equation of a circle centred at the origin is

• x² + y² = r² ( where r is the radius )

• x² + y² = 42.25 ← is in this form

with r² = 42.25 ( take the square root of both sides )

`\rm\sf{r = 42.25}` =
`\sf\red{6.5}`