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5. Find the angles between the following pairs ofvectors :(1) A =î+ſ+k and B = -2 -2 -2 h.(ii) À=-2î + 21 -ħ and B = 3 + 6ſ +2k(iii) A = 2î - 4ſ +6k and B = 3 î + ſ + 2 k. |
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Answer» Explanation: Parallel vector to first line is i ^ + j ^ +2 ^
Parallel vector to second line is ( 3 −1) i ^ −( 3 +1) j ^ +4 k ^
Let the angle between two lines be θ. Then ( i ^ + j ^ +2 k ^ ).(( 3 −1) i ^ −( 3 +1) j ^ +4 k ^ )=∣ i ^ + j ^ +2 k ^ ∣∣( 3 −1) i ^ −( 3 +1) j ^ +4 k ^ ∣cosθ →(6)=( 6 )(2 6 )cosθ →cosθ= 12 6
So, θ=cos −1 ( 2 1 )=60 o |
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