Review_Unit 4_Trig Identities

Answer explanation

Remember the Pythagorean Identity:  $1=\sin^2x+\cos^2x$ 
In this question, all they did was subtract  $\cos^2x$   from both sides. Can you see that?

Simplify

• -1
• sin θ
• csc θ
• 1

Simplify (Hint: you will need to FOIL first)

• sinθ

• cot²θ

• tan²θ

• cos²θ

Multiply and simplify.
(1 - cos x)(1 + cos x)

• sin² x
• cos² x
• tan² x
• csc² x

Use a double-angle or half-angle identity to find the exact value of each expression

cos θ = 4/5 and 270° < θ < 360°Find sin 2θ

• -1/5

• 24/25

• -24/25

• -25/24

Use Sum or Difference Identities to find the exact value of each expression.

cos(75°)

• 1/4

• 
• 
• 

Select all that are reciprocal identities

Which of the following are quotient identities?

Which of the following is the first pythagorean identity? (check all that apply)