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Math has been pretty hard for the past days, and I feel like we just blitzed through this lesson so i am incredibly nervous for tomorrow's test. My teacher though likes getting the hardest items from our textbook and i feel like this item(or something similar to it) might appear.
"Suppose that v and w are unit vectors. If the angle between v and i is (alpha) and if the angle between w and i is (beta), use the idea of dot product v . w to prove that
Cos (alpha - beta) = cos(alpha)cos(beta) sin(alpha)sin(beta)"
I have absolutely no idea on how to start. I tried making cos(alpha) = (v.i)/magnitude(v)magnitude(i) but to no avail
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