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press

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## Homework Statement

Let E be any unit vector, that is a vector of norm 1. Let c be the component

of A along E. We saw that c = A·E. Then A - cE is perpendicular to E, and A = A - cE + cE

Then A - cE is also perpendicular to cE ...

## Homework Equations

## The Attempt at a Solution

I just can't seem to figure where they got A - cE = 0 from. Everyone just shows A - cE = 0 is true on its own instead of showing if c = A·E, then A - cE = 0* which is what I think the author means by "We saw that c = A·E. Then A - cE is perpendicular to E".

Please, elaborate a little. Thanks.

edit: * if c = A·E, then A - cE · E = 0

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