sin(70° a)cos(10° a)-cos(70° a)sin(170°-a)

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/23 23:16:37
sin(70° a)cos(10° a)-cos(70° a)sin(170°-a)
x)+078A!Q39X  nMR>Z lȵG(t2[S5`q0_2@T; bU=lx{ӾObw6 L{: {:A@N~qAb

sin(70° a)cos(10° a)-cos(70° a)sin(170°-a)
sin(70° a)cos(10° a)-cos(70° a)sin(170°-a)

sin(70° a)cos(10° a)-cos(70° a)sin(170°-a)
sin 170度=sin (180度-10度)
=sin 10度,
sin(170°-a)=-sin170度=-sin10度
所以原式=sin(70° a)cos(10° a)+cos(70° a)sin(10° a)=sin(70° a+10° a)=sin80°a