Question

What is the length of the radius of a circle with a center at 2 – i and a point on the circle at 8 + 7i?

Answer 1

10

Explanation:

Answer 2

10

Explanation:

The radius is the magnitude of the complex number that is the difference between any point on the circle and the center point. A suitable calculator can tell you that magnitude:

║(8+7i) - (2-i)║ = √((8-2)² +(7-(-1))²) = √(36+64) = √100 = 10