已知方程sin(α-3∏)=2cos(α-4∏),求[sin(∏-α)+5cos(2∏-α)]/[2sin(3∏/2-α)-sin(-α)]的值

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/24 02:54:31
已知方程sin(α-3∏)=2cos(α-4∏),求[sin(∏-α)+5cos(2∏-α)]/[2sin(3∏/2-α)-sin(-α)]的值

已知方程sin(α-3∏)=2cos(α-4∏),求[sin(∏-α)+5cos(2∏-α)]/[2sin(3∏/2-α)-sin(-α)]的值
已知方程sin(α-3∏)=2cos(α-4∏),求[sin(∏-α)+5cos(2∏-α)]/[2sin(3∏/2-α)-sin(-α)]的值

已知方程sin(α-3∏)=2cos(α-4∏),求[sin(∏-α)+5cos(2∏-α)]/[2sin(3∏/2-α)-sin(-α)]的值
sin(α-3∏)=2cos(α-4∏)
-sinα=2cosα
sinα=-2cosα

[sin(∏-α)+5cos(2∏-α)]/[2sin(3∏/2-α)-sin(-α)]
=(sinα+5cosα)/(-2cosα+sinα)
=(-2cosα+5cosα)/(-2cosα-2cosα)
=-3/4

变换,把原方程改改咯.