Find the three angles of the triangle with given vectors.(adsbygoogle = window.adsbygoogle || []).push({});

A(1,0)

B(3,6)

C(-1,4)

I found that AB & BC are congruent, so this ends up being an Isosceles triangle and the only angle I need to find is B.

BC=<3+1,6-4>=<4,2>

AB=<3-1,6-0>=<2,6>

[tex]\angle B=\cos^{-1}{\frac{20}{\sqrt{20 \cdot 40}}=45^o[/tex]

So [tex]\angle A = \angle C = \frac{180-45}{2}=67.5^o[/tex] but this isn't correct, so what am I doing wrong?

It's supposed to be a 45, 45, 90 triangle.

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# Homework Help: Dot Product, what's wrong with my method?

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