let y=cos(x+180/12)cos(x-180/4)
express y in the form a cos(2x+b)+c, where a, b and c are constants
urgent!1 trigonometric short q
2011-03-18 5:45 am
回答 (1)
2011-03-18 5:51 am
✔ 最佳答案
cos(x + π/12)cos(x - π/4)= (1/2)[cos(2x + π/12 - π/4) + cos(π/12 + π/4)]
= (1/2)[cos(2x - 2π/12) + cos(4π/12)]
= (1/2)cos(2x - π/6) + 1/4
a = 1/2, b = -π/6, c = 1/4
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https://hk.answers.yahoo.com/question/index?qid=20110317000051KK01226