Question

calculati cos²120+sin²60

Answer 1

cos120 = cos( 180 - 60) =  - cos60
cos²120 + sin²60 = [ - cos60 ]² + sin²60 = cos²60 + sin²60 = 1

Answer 2

[tex]cos^2 120 +sin^2 60 [/tex]

Conform formulei $sin^2x +cos^2x=1$

120+60=180 (grade)


cos 120=cos(180-60)= cos 180*cos60-sin 180*sin 60 =-cos60


[tex]cos^2 120 +sin^2 60 [/tex]


cos^2 60 + sin^2 60 =1