Observe the figure:

The sides of the triangle are and .

Find .

                                  (Pythagorean theorem)

                             (Substitute and )

                              (Evaluate powers and )

              (Subtract from each side)

                              (Apply additive inverse property: )

                                      (Subtract : )

                               (Take the square root of each side)

                                    (Cancel square root)  

                                 (Using caluculator: )

Length cannot be negative, so the missing length is .

.