Answer:
radius = 6.5
Step-by-step explanation:
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 )
r = [tex]\sqrt{42.25}[/tex] = 6.5
