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Question
Find the value λ for which the vectors `vec"a"` and `vec"b"` are perpendicular, where `vec"a" = 2hat"i" + lambdahat"j" + hat"k"` and `vec"b" = hat"i" - 2hat"j" + 3hat"k"`
Solution
When `vec"a"` and `vec"b"` are ⊥r then `vec"a"*vec"b"` = 0
`vec"a"` ⊥r `vec"b"` ⇒ `vec"a" * vec"b"` = 0
(2)(1) + (λ)(– 2) + (1)(3) = 0
⇒ λ = `5/2`
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