1.

If sinbeta is geometric mean between sin alpha and cos alpha ,then cos 2beta =

Answer»

`2sin^2(pi/4-alpha)" or " 2 cos^2(pi/4+alpha)`
`2sin^2(pi/3-alpha)" or " 2 cos^2(pi/3+alpha)`
`sin^2(pi/4-alpha)" or "cos^2(pi/4+alpha)`
`sin^2(pi/3-alpha)" or " 2 cos^2(pi/3+alpha)`

ANSWER :A


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