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Using the Pythagorean Theorem to Find Side Lengths

The Pythagorean Theorem can be used when one of the side lengths is not known.

Example:
Find the missing side length.

Right triangle

Solution:
The missing side length is one of the legs.  Let’s use x to represent this side length.

x² + 232 = 292
x² + 529 = 841
x² = 312
x =  ≈ ±17.66
x ≈ 17.66

**Notice when we solved this equation, we did not include the negative answer.  Side lengths can only be positive, so only the positive answer is valid.

The missing side length is approximately 17.66 ft.