Question

Rewrite 2sin2x + 3 cos x − 3 in terms of cos x

Answer 1

-2cos(x)+3cos(x)-1

Explanation:

Answer 2

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Answer:

-2cos²(x) +3cos(x) -1

Explanation:

Use the "Pythagorean identity" to replace sin²(x).

sin²(x) +cos²(x) = 1

Then ...

2sin²(x) +3cos(x) -3 = 2(1 -cos²(x)) +3cos(x) -3

= -2cos²(x) +3cos(x) -1