(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Under what conditions are the following true?

a) [tex]|\mathbf{a}\cdot \mathbf{b}| =|\mathbf{a}||\mathbf{b}|[/tex]

b) [tex](\mathbf{a} + \mathbf{b}) \cdot (\mathbf{a} - \mathbf{b}) = |\mathbf{a}|^2 - |\mathbf{b}|^2[/tex]

2. Relevant equations

None.

3. The attempt at a solution

a) I dont understand why the answer is [tex]\mathbf{a} = \lambda \mathbf{b}[/tex]. Surely it would be equivalent all the time?

b) Also looks equivalent all the time to me.

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# Homework Help: Conditions of dot product

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