Question

calcule
a) cos 105.

Answer 1

cos (105)

cos(45+60)= 

cos60.cos45 - sen60.sen45 = 

1/2 . √2 /2 - √3 /2 . √2 /2 =


√2 /4 - √6 / 4 ]=


(√2 - √6) / 4 

Bons estudos!