Question

Find the angle between A = 2i-3j+4k and B = -i+5j-3k​

Answer 1

Answer:

let this vector to be dot products ::  

so a →. b → = 2 × -1  -3 × 5  - 4× 3

= -2 -15 -12

= -29

so ... now

mag a = $\sqrt{4+9+16 } = \sqrt{29}$

mag b = $\sqrt{1+25+9} = \sqrt{35}$

now ...

a→·b→ = mod (ab) cos∅

-29 = √1015 cos∅

∅$= - cos^{-1} 29/ \sqrt{1015 }$