Science:Math Exam Resources/Courses/MATH152/April 2016/Question A 21/Hint 3

Let ${\pi }_1$ denote the projection onto $L_1$ and let ${\pi }_2$ denote the projection onto $L_2$. Use the geometric interpretation of projection onto a line to determine the range of ${\pi }_1$. Then, use the same argument, and the fact that $L_1$ and $L_2$ are perpendicular, to determine the range of ${\pi }_2\circ {\pi }_1$.