Architects and construction workers rely on geometric formulas when designing and constructing buildings so that they know how much they need in materials and so they can build the structure safely. One formula that can come into play is measuring the radius of a curved wall. The radius is half the diameter, or length of the circle.

## Step 1

Measure the distance across the front of the wall, making a straight line from one side of the wall to the other. This is called a chord. In this example, the chord is 10 feet.

## Step 2

Measure the depth of the wall by measuring the distance from the front edge of the chord to the top of the arc. In this example, the depth of the wall is 4 feet.

## Step 3

Divide the height of the wall by 2.

4 / 2 = 2

## Step 4

Square the width of the chord.

10 * 10 = 100

## Step 5

Multiply the height of the wall by 8.

4 * 8 = 32

## Step 6

Divide the result you got from squaring the chord by the result you got from multiplying the height by 8.

100 / 32 = 3.125

## Step 7

Add the number you got from dividing the height by 2 and the number you got from the last step to determine the radius.

2 + 3.125 = 5.125

The radius of the wall is 5.125 feet.