How to Measure a Flagpole

You can measure a flagpole by its shadow.
••• Stars and stripes USA flag on a flagpole image by Steve Johnson from Fotolia.com

You can easily measure the height of a flagpole without having to climb it by using the rule of similar triangles. The idea is that if two triangles have the same three angles, then the ratio between the sides’ lengths is the same between triangles as well. For example, if two triangles have angles 45, 45 and 90 degrees, then the two sides other than the hypotenuse are equal in each triangle.

    Measure the length of the shadow cast by the flagpole on a sunny day. Use a yardstick or meter stick to do this. Denote the length with the letter S, for “shadow.”

    Plant a stick vertically in the ground near the flagpole. Measure the length of its shadow and denote it with the lowercase letter s, to stand for smaller shadow.

    Measure the stick’s vertical height. Denote it with the letter h.

    Calculate the flagpole’s height, H, using the formula H/S = h/s. In other words, H = h(S/s).

    For example, if S is 15 feet, h is 4 feet (perhaps you used a yardstick as the stick) and s is 3 feet. Then H is 4*(15/3) = 20 feet tall. This is the height of the flagpole.

    Things You'll Need

    • Measuring tape
    • Stick
    • Yardstick or meter stick

    Tips

    • The straighter, taller and more vertical the stick, the better will be the accuracy of your h and s measurement. You can use a level to make sure the stick is vertical.

Related Articles

How to Calculate Height
How to Calculate Angles Without a Protractor
How to Calculate Pendulum Force
How to Calculate Width
How to Calculate Tree Basal Area
How to Measure the Height of a Flagpole
How to Find the Missing Side of a Right Triangle
Names of Tools Used to Measure Angles
How to Calculate the Diameter of a Rectangle
How to Calculate Ramp Length
How to Calculate Area of a Triangle
How to Bisect a Triangle
How to Use a Protractor to Measure a Triangle
How to Calculate the Length of Cable on a Drum
Test Your Knowledge on Middle School Science
How to Find the Area & Width of a Rectangle
How to Calculate Sides of a Triangle
How to Find the Volume of a Sphere in Terms of Pi
How to Find Mass in Weight
How to Measure the Length of the Diagonal Line of a...

Dont Go!

We Have More Great Sciencing Articles!