Answer:
radius =
Step-by-step explanation:
The equation of a circle in standard form is
(x - h)² + (y - k)² = r²
where (h, k) are the coordinates of the centre and r is the radius
(x - 1)² + (y + 3)² = 73 ← is in standard form
with r² = 73 ( take the square root of both sides )
r =