cos^2 5π/12-sin^2 7π/12=? 求详细过程_其他解答

cos^2 5π/12-sin^2 7π/12=? 求详细过程

人气：323 ℃　时间：2020-05-07 17:31:43

解答

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