Canada Builds

Measuring Height

The law of Tangents can help you to measure the height of a building without having climb great heights.

Measure horizontally along the ground from the building to some point. In this example, a value of 30 metres is used but it could be anything. 30 m is the value for 'b' in the diagram below.

From this point, measure the angle created to sight the top of the building. In the example below a value of 31.66 degrees is indicated. these two values, the horizontal distance and the angle to the top of the building can now be used to calculate the height (a).

The excel worksheet below can be used to help you calculate the height of a large object such as a building, a tree or a mountain. The horizontal distance is lowercase 'b' and the angle is uppercase 'A' in degrees. These two values are shown in red below and the height is then calculated using the law of tangents.