Evaluate and simplify cos(-15º). Hint: Substitute 30º-45º for -15º.
Well, why not follow that hint
sin(-15) = sin(30 - 45)
= sin30cos45 - cos30sin45
= ....
You should know the trig functions of those special angles.
sin(-15) = sin(30 - 45)
= sin30cos45 - cos30sin45
= ....
You should know the trig functions of those special angles.