已知sin(π/2+α)-cos(3π/2-α)=1/5(π/2_数学解答

已知sin(π/2+α)-cos(3π/2-α)=1/5(π/2

人气：373 ℃　时间：2020-01-26 15:06:54

解答

==》cosa+sina=1/5cos^a+2cosasina+sin^a=1+2cosasina=1/25cosasina=-12/25cosa<0,-sina<0 1-2cosasina=(cosa-sina)^=49/25cosa-sina=-7/25tana=sina/cosa=-12/2=-6(π/2cos(3π/2-α)=sina