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When sin (x + Pie / 2) = 1 / 3, the value of COS (x + Pie / 12) is?
If sin (x + π / 2) = cosx = 1 / 3, then SiNx = soil 2 √ 2 / 3, cos (7 π / 12) = cos (π / 3 + π / 4) = (√ 2 - √ 6) / 4, sin (7 π / 12) = (√ 2 + √ 6) / 4, cos (x + 7 π / 12) = cosxcos (7 π / 12) - sinxsin (7 π / 12) = (√ 2 - √ 6) / 12 dry (4 + 4 √ 2) / 12 = (- 4-3 √ 2 - √ 6) / 12
Cos ^ 2 5 π / 12-sin ^ 2 7 π / 12 =? Detailed process
con²(5π/12)-sin²(7π/12)=cos²(5π/12)-sin²(π-7π/12)=cos²(5π/12)-sin²(5π/12)=cos(2*5π/12)=cos(5π/6)=-(√3)/2
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