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3 votes
Convert this identity to one using sine term(s) only.
1-2cos(r)^2

1 Answer

4 votes
Pythagorean identity:
sin²+cos²=1
Then cos²=1-sin²
Substitute:
1-2cos²
1-2(1-sin²)
1-2+2sin²
2sin²-1
User MrBliz
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