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morsel
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Homework Statement
Let A be the matrix of an orthogonal projection. Find A^2 in two ways:
a. Geometrically. (consider what happens when you apply an orthogonal projection twice)
b. By computation, using the formula:
matrix of orthogonal projection onto V = QQ^T, where Q = [u1 ... um]
Homework Equations
The Attempt at a Solution
I have no idea how to approach (a).
(b). A^2 = Q Q^T Q Q^T = Q^2 (Q^T)^2
Thanks in advance.