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

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

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

Prove that cos^2alpha+cos^2(120^@-alpha)+cos^2(120^@+alpha)=3/2

cos ^(2) alpha + cos ^(2) (alpha + 120^(@)) + cos ^(2) (alpha - 120^(@)) is equal to

cos ^(2) alpha + cos ^(2) (alpha + 120^(@)) + cos ^(2) (alpha - 120^(@)) is equal to

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

( cos 2 alpha)/( cos^(4) alpha - sin^(4) alpha ) -(cos^(4) alpha + sin^(4) alpha )/(2-sin^(2) 2alpha ) =

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)

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

sin^(2) alpha * tan alpha + cos^(2) alpha * cot alpha + 2 sin alpha cos alpha =