(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8).

来源:学生作业帮助网 编辑:六六作业网 时间:2024/07/08 18:22:09
(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8).(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8).(cosπ/8+sinπ/8)(cos^3π/8-sin^3

(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8).
(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8).

(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8).
(cosπ/8+sinπ/8)(cos^3π/8-sin^3π/8)
=(cosπ/8+sinπ/8)(cosπ/8-sinπ/8)(cos^2π/8+cosπ/8*sinπ/8+sin^2π/8)
=(cos^2π/8-sin^2π/8)(1+0.5sinπ/4)
=cosπ/4(1+0.5sinπ/4)
=根下2/2(1+根下2/4)
=根下2/2+1/4.