We have the formula for the area of a triangle equal to A=l*w, where stands for the area, l for the length and w for the width. Given in the problem are the following: A=135 m l=6+w w=w Solving for the value of w, we have: A=(w+6)*w 135=w²+6w w=9 meters Therefore, the length of the rectangle is 15 meters.