Question

What is the radius of circle c

Answer 1

Answer:

radius = 13

Step-by-step explanation:

Look at the attached picture below. We can calculate radius with the help of the Pythagorean theorem. But first we have to find out the values of the two legs.

First let's find the shorter leg.

Equidistant Chords Theorem

Two chords are congruent if they are equidistant from the center.

Chords in the picture are congruent and that means that the distance from the center to each of them is the same!

Let's calculate the distance. But to get the distance we have to find x first.

Since the distances are the same:

$x + 3 = 2x + 1\\2 = x$

Therefore:

$\text{distance (short leg)} = 2x + 1 = 2\cdot2 + 1 = 5$

Let's focus on the longer leg. Since part of the radius is perpendicular to the chord, it actually bisects the chord! That means that the long leg is going to be a half of the length of the chord.

Therefore:

$\text{long leg} = \frac{\text{chord}}{2} = \frac{24}{2} = 12$

All that is left is the Pythagorean Theorem in the right triangle.

Pythagorean Theorem

$\text{hypotenuse}^2 = \text{leg}_1^2 + \text{leg}_2^2$

Hypotenuse in our case is the radius.

$\text{radius}^2 = 5^2 + 12^2\\\text{radius}^2 = 25 + 144\\\text{radius}^2 = 169\\\text{radius} = 13$