# Find the radius of the circle if the center is at (1, 2) and the point (-3, 4) lies on the circle?

**Solution:**

Given the center is at (1, 2)

The point (-3, 4) lies on the circle

Radius can be calculated as the distance between the centre to any point on the circle.

Radius = √{(y\(_2\) - y\(_1\))^{2} + (x\(_2\) - x\(_1\))^{2}}

= √{(4 - 2)^{2} + (-3 - 1)^{2}}

= √{ 4 + 16}

= √20

Radius = √20 = 2√5

## Find the radius of the circle if the center is at (1, 2) and the point (-3, 4) lies on the circle?

**Summary:**

The radius of the circle if the center is at (1, 2) and the point (-3, 4) lies on the circle is 2√5