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Find vecA*vecB if |vecA|= 2, |vecB|= 5, ...

Find `vecA*vecB` if `|vecA|= 2, |vecB|= 5, and |vecAxx vecB|=8`

Text Solution

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The correct Answer is:
`vecA*vecB= pm 6`
As `" "|vecAxx vecB| ^(2) = |vecA|^(2) |vecB|^(2) - (vecA*vecB)^(2)`
`therefore 8^(2) = 2^(2) xx 5^(2) - (vecA*vecB)^(2) `
`rArr (vecA*vecB)^(2) = 100 -64 =36`
`therefore " "vecA*vecB = pm 6`
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