Suppose (l_{1}, m_{1}, n_{1}) and (l_{2}, m_{2}, n_{2}) are the directional cosines of two lines and \theta is the angle between them and \cos \theta=\pm(l_{1} l_{2}+m_{1} m_{2}+n_{1} n_{2}). Let {A}=(1,-2,3), {B}=(3,1,-3) and {C}=(-3,1,3) be the vertices of a triangle {ABC}. Then \cos {A}=

AP EAPCET 07-Jul-2022 Shift 1 Paper

Section: Mathematics

Question : 57 of 160

Marks: +1, -0

Suppose (l1,m1,n1) and (l2,m2,n2) are the directional cosines of two lines and θ is the angle between them and cos‌θ=±(l1l2+m1m2+n1n2). Let A=(1,−2,3), B=(3,1,−3) and C=(−3,1,3) be the vertices of a triangle ABC. Then cos‌A=

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35
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7
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35

Validate

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