作业帮19题范围是0~兀
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/07/14 05:26:23
19题范围是0~兀
18.f(x)=cos(x)+sin(x)+a^2*sin(x+π/4)=2^0.5*sin(x+π/4)+a^2*sin(x+π/4)=(2^0.5+a^2)sin(x+π/4)
所以 f(x)max=2^0.5+a^2=2^0.5+3 所以a=3^0.5
19.原式=(1+2sin(a/2)cos(a/2)+2cos(a/2)^2-1)(sin(a/2)-cos(a/2))/(2+2(2cos(a/2)^2-1))^0.5
=2cos(a/2)(sin(a/2)+cos(a/2))(sin(a/2)-cos(a/2))/(2cos(a/2))
=sin(a/2)^2-cos(a/2)^2
=-cosa
!
所以 f(x)max=2^0.5+a^2=2^0.5+3 所以a=3^0.5
19.原式=(1+2sin(a/2)cos(a/2)+2cos(a/2)^2-1)(sin(a/2)-cos(a/2))/(2+2(2cos(a/2)^2-1))^0.5
=2cos(a/2)(sin(a/2)+cos(a/2))(sin(a/2)-cos(a/2))/(2cos(a/2))
=sin(a/2)^2-cos(a/2)^2
=-cosa
!