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Adrian S
Lv 7
Find the exact value of sin(7.5 deg). Show work need ASAP. Hint 2*7.5 = 15. No calculator?
Use trig formulas, etc but no calculator answer.
Update:
The first answer provided was not correct. I've been able to solve it myself using half and double angle formulas for cos.
1 Answer
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- CogentLv 41 decade agoFavorite Answer
Use the following formulae:
2 sin² θ/2 = 1 + cos θ
2 cos² θ/2 = 1 - cos θ
cos 15º = √[(1 - cos 30º)/2] = √[(1 - √3/2)/2] = [√(2 - √3)]/2 = (√3 - 1)/2
sin 7.5º = √[(1 + cos 15º)/2] = [√(1 + √3)]/2
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