Find the exact value of cos (75°).
Hint
The addition formula for cosine is cos (α + β) = cos (α) cos (β) – sin (α) sin (β).
Answer
Find the exact value of sin (105°).
The addition formula for sine is sin (α + β) = sin (α) cos (β) + cos (α) sin (β).
Simplify tan (x - 30°).
The subtraction formula for tangent is .
Find the exact value of sin 195°.
The reference angle for this angle is 15°, and it is in Quadrant III.
Simplify cos (x – π).
This simplifies to a single trig function.
-cos x
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