How To Determine The Radius Of A Curved Wall
Things Needed

Tape measure

Calculator
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.
Tip
If the arc of the wall is 180 degrees or greater, measure the distance across the wall at it's widest point. Divide that distance by 2 to calculate the radius. If the arc of the wall is less than 180 degrees, calculate the radius by using the process described above.