Hello, dvh9!

A bridge over a river has a shape of a circular arc.

The span of the bridge is 24 meters. (The span is the length of the chord of the arc.)

The midpoint of the arc is 4 meters higher than the endpoints.

What is the radius of the circle that contains this arc? Code:

C
* * *
* 4| *
A *-------o-------* B
* * 12 |D * *
* | * R
* * | * *
* - - - - * - - - - *
O

The center of the circle is

The radius is: .

, hence: .

In right triangle

So we have: .

. .

Therefore, the radius of the arc is 20 meters.