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 .

.

.