" 16."cos^(2)(60^(@)+alpha)+cos^(2)(60^(@)-alpha)+cos^(2)alpha" बराबर है : "

4sin(420^(@)-alpha)cos(60^(@)+alpha)=

cos^(2)(45^(@)-alpha)+cos^(2)(15^(@)+alpha)-cos^(2)(15^(0)-alpha)=

4 sin (420^(@) - alpha ) cos (60^@ + alpha ) =

cos^(2) ( 45^(@) - alpha ) + cos^(2) (15^(@) + alpha ) - cos^(2)(15^(@)-alpha)=

cos^(2)(alpha+beta)+cos^(2)(alpha-beta)-cos2alpha cos2beta=

Show that, cos^(2)alpha + cos^(2) (120^(@) - alpha) + cos^(2) (120^(@) + alpha) = 3/2.

cos^(2)alpha+cos^(2)(alpha+120^(@))+cos^(2)(alpha-120^(@))=?

cos alpha cos(60^(@) - alpha ) cos (60^(@) + alpha ) = 1/4 cos 3 alpha.

To prove ((1)/(sec^(2)alpha-cos^(2)alpha)+(1)/(cos ec^(2)alpha-sin^(2)alpha))cos^(2)alpha sin^(2)alpha=(1-sin^(2)alpha cos^(2)alpha)/(2+sin^(2)alpha cos^(2)alpha)