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If a line makes angles alpha,betaa n dga...

If a line makes angles `alpha,betaa n dgamma` with threew-dimensional coordinate axes, respectively, then find the value of `cos2alpha+cos2beta+cos2gammadot`

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`cos2alpha+cos2beta+cos2gamma`
`" "=2cos^(2)alpha-1+2cos^(2)beta-1+2cos^(2) gamma-1`
`" "=2(cos^(2)alpha+cos^(2)beta+cos^(2)gamma)-3` ltBrgt `" "=-1`
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