Tagged Questions
12
votes
12answers
2k views
Funny thing. Multiplying both the sides by 0?
Alright this maybe really funny but I want to know why is this wrong. We often come across identities which we prove by multiplying both the sides of the identity by a certain entity but why don't we ...
1
vote
2answers
116 views
Vector Identity and the Scalar Product
Ok, I have a question that probably has a very simple answer but for some reason I can't see it. Let $a$ and $r$ be two vectors of nonzero length with a common origin and let $\theta$ be the nonzero ...
4
votes
1answer
296 views
What's wrong with this proof that $e^{i\theta} = e^{-i\theta}$?
I recently learned that $\cos{\theta} = \frac{e^{i\theta} + e^{-i\theta}}{2}$ and $\sin{\theta} = \frac{e^{i\theta} - e^{-i\theta}}{2}$ Based on this, I managed to "prove" that:
$$e^{i\theta} = ...
