Question

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

circle.

Answer 1

The distance between these two points is the radius of the circle. The pyth. theorem is useful in solving this problem. You need to construct a right triangle first where the hypotenuse is the length between the points.

The two other side lengths: 1-(-3)=4 and 4-2=2

Now let us use the pyth. theorem to find the hypotenuse:

x^2=4^2+2^2

x^2=20

x=√20

x=2√5

radius = 2√5

Answer 2

Explanation:

Calculate distance from (1,2) to (-3, 4)

the x values, 1 and -3, are 4 units apart from each other.

the y values, 2 and 4, are 2 units apart from each other.

create a triangle using the distances, where 4 is the horizontal and 2 is the vertical. then use Pythagorean theorem to solve for hypotenuse (radius)

2^2 + 4^2 = 20

√20 = 4.47