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Question
If `|vec"a"| = 4, |vec"b"| = 3` and `vec"a".vec"b" = 6 sqrt(3)`, then find the value of `|vec"a" xx vec"b"|`.
Solution
As `vec"a".vec"b" = |vec"a"||vec"b"| cos theta = 6sqrt(3)`
⇒ `4 xx 3 xx cos theta = 6sqrt(3)`
⇒ `cos theta = sqrt(3)/(2)`
∴ sin θ = `(1)/(2).`
Now,
`|vec"a" xx vec"b"| = |vec"a"||vec"b"| sin theta = 4 xx 3 xx (1)/(2) = 6`.
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