Question Detail
Question
Find the equation of a circle whose diameter has the ends (-5, 1) and (3, -7).
Correct Answer
Option C is the correct answer.
Detailed Explanation
Center is midpoint: ((-5+3)/2, (1+(-7))/2) = (-2/2, -6/2) = (-1, -3). Radius = half the distance between endpoints: distance = √[(3-(-5))² + (-7-1)²] = √[8² + (-8)²] = √(64+64) = √128 = 8√2. Radius = 4√2. Equation: (x+1)² + (y+3)² = 32 → x² + 2x + 1 + y² + 6y + 9 = 32 → x² + y² + 2x + 6y + 10 - 32 = 0 → x² + y² + 2x + 6y - 22 = 0.
Hint
The center is the midpoint of the diameter endpoints.