Answer:
r = 17 units
Step-by-step explanation:
The radius is the distance from the centre (- 7, - 1) to the point on the circle
(8, 7)
Use the distance formula to calculate the radius (r)
r = √ (x₂ - x₁ )² + (y₂ - y₁ )²
with (x₁, y₁ ) = (- 7, - 1) and (x₂, y₂ ) = (8, 7)
r = [tex]\sqrt{(8+7)^2+(7+1)^2}[/tex]
= [tex]\sqrt{15^2+8^2}[/tex]
= [tex]\sqrt{225+64}[/tex]
= [tex]\sqrt{289}[/tex] = 17 units
