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**1. (A) sin(-x) = - sin x (C) cos(x+y) = cosxcosy - sinxsiny**

(B) cos(-x) = - cos x (D) sin(x+y) = sinxcosy + cosxsiny

Use these equalities to derive the following trigonometric identities.

a. absolute value of cos x/2 = [tex]\sqrt{}1 + cosx/2[/tex]

b. absolute value of sin x/2 = [tex]\sqrt{}1 - cosx/2[/tex]

(B) cos(-x) = - cos x (D) sin(x+y) = sinxcosy + cosxsiny

Use these equalities to derive the following trigonometric identities.

a. absolute value of cos x/2 = [tex]\sqrt{}1 + cosx/2[/tex]

b. absolute value of sin x/2 = [tex]\sqrt{}1 - cosx/2[/tex]

**2.above**

**3. I'm stuck on these two and tried to think of different ways to solve it but I can't seem to get find a solution to it. Can you please explain how to derive those two equations? Thank You!!**