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 .

.

.