How do you do #9? Ignore the rest of the problems

Question

asked Feb 7, 2024 157k views

1 Answer

Jonathan Wilbur · Answer 1 · 2024-02-11T21:10:53+0000

Explanation:

cos (105) = cos( 60 + 45) = cos 60 cos 45 - sin60 sin45

= 1/2 * sqrt (2) /2 - sqrt(3)/2 * sqrt (2)/2

= sqrt (2)/4 - sqrt(6)/4

= 1/4 (sqrt(2) - sqrt (6) )