Упростите выражение: 1)Cos^4*2x-sin^4*2x 2)cos2a/cosa-sin2a/sina 3)1+cos2x+2sin^2x 4) 2sin^2a-1 5)sin^2x+Cos^4x-0.75 6)2cos^x-1 Заблаговременно спасибо!

1 ) Cos ^ 4 * 2x - sin ^ 4 * 2x = ( cos2x ^ 2 + sin2x ^ 2 ) * ( cos2x ^ 2 - sin2x ^ 2 ) = 1 * ( cos2x ^ 2 - sin2x ^ 2 ) = ( cos2x ^ 2 - sin2x ^ 2 ) = cos ( 2 * 2x ) = cos ( 4 * x ) ;
2 ) cos2a / cosa - sin 2a / sina = ( cos2a * sina - sin2a * cosa ) / ( cos a * sin a ) = - ( sin2a * cosa - cos2a * sina ) / ( cos a * sin a ) = - ( sin ( 2 * a - a ) / ( cos a * sin a ) = - ( sin a / ( cos a * sin a ) = - 1 / cos a ;
3 ) 1 + cos2x + 2 * sin ^ 2x = sin x ^ 2 + cos x ^ 2 + cos x ^ 2 - sin x ^ 2 + 2 * sin x ^ 2 = 2 * cos x ^ 2 + 2 * sin x ^ 2 = 2 * ( cos x ^ 2 + sin x ^ 2 ) = 2 * 1 = 2 ;
4) 2 * sin ^ 2a - 1 = 2 * sina ^ 2 - cosa ^ 2 - sina ^ 2 = sina ^ 2 - cosa ^ 2 = - ( cos a ^ 2 - sin a ^ 2 ) = - cos ( 2 * a );
5 ) sin ^ 2x + Cos ^ 4x - 0 . 75 = sin x ^ 2 + 1 - sin x ^ 2 - 0 . 75 = 1 - 0 . 75 = 0. 2 5 ;
6 ) 2 * cos ^ 2 x - 1 = 2 * cosx ^ 2 - sinx ^ 2 - cosx ^ 2 = cosx ^ 2 - sinx ^ 2 = cos( 2 * x ).