Question

find angle between two vectors A= 2i+3j-4k ,B= 2i-4j+5k
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Answer 1

Explanation:

A = 2i + 3j - 4k , B = 2i -4j + 5k

A.B = 4 i^2 - 12 j^2 -20 k^2

A.B = 4 -12 -20 = -28

|A| = √(4 + 9 + 16) = √29

|B| = √(4 + 16 + 25) = √45

therefore,

$\cos( \beta ) = \: \frac{a.b}{ |a| |b| }$

cos beta = -28 / √29 × √50

beta = cos inverse [-28/√1450]

on solving above statement,

beta = 43.2 degrees