Question

What is the radius of the circle: x^2+y^2=4

1. (0, -4)
2. (0, 4)
3. (2, -4)
4. (0, 0)

Answer 1

radius = 2

Explanation:

The equation of a circle centred at the origin is

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

x² + y² = 4 ← is in this form

with r² = 4 ⇒ r =
`√(4)` = 2

centre (0, 0 ) and radius = 2