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unicwaan
 one year ago
Can someone help me answer a precalculus question please?
unicwaan
 one year ago
Can someone help me answer a precalculus question please?

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unicwaan
 one year ago
Best ResponseYou've already chosen the best response.0Find the angle between the given vectors to the nearest tenth of a degree. u = <2, 4>, v = <3, 8>

anikhalder
 one year ago
Best ResponseYou've already chosen the best response.1You can write u as 2i 4j and v as 3i 8j. Then you can apply the dot product rule to find the angle. Take a look at this page: http://www.wikihow.com/FindtheAngleBetweenTwoVectors Or take a look at these videos. It will really make your base strong. https://www.khanacademy.org/math/linearalgebra/vectors_and_spaces

IrishBoy123
 one year ago
Best ResponseYou've already chosen the best response.2you don't have to rewrite them, this is really good compact notation you are using: \(\large \vec u = <2, 4>, \vec v = <3, 8>\) for \(\large \vec u = <u_x, u_y>, \vec v = <v_x, v_y>\), we have \(\large \vec u \bullet \vec v = u_x \times v_x + u_y \times v_y = \vec u\vec v cos \theta\). \(\large \theta \) is the angle between these vectors. \(\large \vec u\) is the magnitude of \(\large \vec u\) and equals \(\large \sqrt {u_x^2 + u_y^2}\), ditto for \(\large \vec v\). that's all you need to answer this, but you should always check first for some trickery in the question, eg where they are clearly parallel.

IrishBoy123
 one year ago
Best ResponseYou've already chosen the best response.2@anikhalder thanks for the medal! have one back :p

anikhalder
 one year ago
Best ResponseYou've already chosen the best response.1Thank you very much. I really appreciate your explanation and I hope rather than the medals our mutual friend here won't be having troubles finding the angle between vectors anymore :)))
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