Question

What is the radius for a circle whose equation is x² + y² = 64?

A. 8
B. 16
C. 64
D. 32

Answer 1

A

Explanation:

the equation of a circle centred at the origin is

x² + y² = r² ( r is the radius )

x² + y² = 64 ← is in this form

with r² = 64 ( take square root of both sides )

r =
`√(64)` = 8