Identify the two perpendicular sides of the right triangle
Label them as a and b
Identify the longest side opposite the right angle
Label it as c
Use the formula a² + b² = c²
Substitute the known side lengths into the formula
Square the two shorter sides
Add the squared values
If solving for the hypotenuse, take the square root of the sum
If solving for a missing leg, subtract the known square from c²
Take the square root of the result
Check that the side lengths form a right triangle if needed