4.9-1/化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/05/15 06:36:03

4.9-1/化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].
做出来都是1+sin(2a)

[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)]
=[cos(2a+30)+1]/2+[1-cos（2a-30)]/2+1/2sin2a
=1+[cos(2a+30)-cos(2a-30)]/2+1/2sin2a
=1-2sin2a*sin30/2+1/2sin2a
=1

4.9-1/化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a- 化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)] 化简cos^2(a+15)+sin^2(a-15))+sin(a+180)cos(a-180) 化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180) sin(a+105度)cos(a-15度)-cos(a+105度)sin(a-15度) 化简Sin A + Sin 2A / 1+cos A + 化简sin(a-15度)cos（a+15度）+cos（a-15度)sin(a+15度) 化简:1,sin(pai/4-x)sin(pai/4+x) 2,cosA+cos(120度-A)+cos(120度+A) 证明Cos^A-Sin^A=1-2Sin^A=2Cos^A-1=cos^a-sin^a 化简：sin 2a/(1+cos 2a) * cos a/(1+cos a) 化简:sin(-a)cos(2π+a)sin(-a-π) 化简 1-sin^4a-cos^4a/cos^2a-cos^4a