Answer:
Radius r = 5
Equation
x² + y² = 25
Explanation:
Equation of a circle in standard form is
(x - a)² + (y - b)² = r²
where
(a, b) is the center of the circle
r is the radius
Plugging in (a, b) = (0, 0) we get
((x - 0)² + (y - 0)² = r²
x² + y² = r² [1]
Since (-4, - 3) is a point on the circle, these coordinates should satisfy the circle equation for x = - 4 and y = - 3
Plugging in these values into equation [1]:
(-4)² + (-3)² = r²
or
r² = (-4)² + (-3)²
r² = 16 + 9
r² = 25
r = ± √25
r = ± 5
Ignoring the negative value we get
r = 5
Equation is
x² + y² = 25