1. Ապացուցել նույնությունը

ա) cos4a – sin4a = cos2a

(cos2a – sin2a) * (cos2a + sin2a) = cos2a

cos2a – sin2a = cos2a

cos2a = cos2a

cos2a – 1 + cos2a = cos2a

2cos2a – 1 = cos2a

Ապացուցված է

բ) (tga + ctga) * sin2a = 2

գ) cos2a/1 + sina + sina = 1

sina/cosa + cosa/sina/cosa/sina + sina/cosa = sin2a + cos2a/cosa sina/sin2a + cos2a/cosa sina = cos2a + sin2a/sin2 * cos2 = 1

Ապացուցված է

դ) ctga – tga/ctga + tga = cos2a

cosa/sina – sina/cosa/cosa/sina + sina/cosa = cos2a – sin2a/sina cosa/cos2a + sin2a/sina cosa = cos2a – sin2a/1 = cos2a

Ապացուցված է