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: )

                                       (Subtraction: )

                                (Take the square root of each side)

                                     (Cancel square root)  

                                  (Using caluculator )

Length cannot be negative, so the missing length is .

.

.