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If 2 cos alpha = x + (1)/(x) and 2 cos b...

If 2 cos `alpha` = x + `(1)/(x)` and 2 cos `beta` = y + `(1)/(y)`, show that
`x^(m) y^(n) + (1)/(x^(m)y^(n)) = 2 cos (m alpha + n beta)`

Text Solution

Verified by Experts

The correct Answer is:
`x^(m)y^(n)+(1)/(x^(m)y^(n))=2cos(malpha+nbeta)`
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