Question 1036736: Please help me solve this :
Solve cos 155° + cos 65°
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website! -0.483690
NOTE: Why is it negative? angles are measured from 0 to 360°, but sin(θ) and cos(θ) are only defined for 0 to 90°. When either the sin or cos are negative, the angle (θ) is larger than 90 degrees, and such angles never appears in any right-angled triangle.
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