化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].请大家解释一下.[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=1-2si

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化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].请大家解释一下.[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=1-2si
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化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].请大家解释一下.[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=1-2si
化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].
请大家解释一下.
[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
第一步有点看不懂 用的是什么公式啊

化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].请大家解释一下.[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=1-2si
[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（倍角公式 ）
=1+[cos(2a+30)-cos(2a-30)]/2+1/2sin2a
=1-2sin2a*sin30/2+1/2sin2a
=1
sin(a+180度)cos(a-180度)
= [sin(a+180度+a-180度)+sin(a+180度-a+180度)]/2
=[sin2a+sin360]/2
=1/2sin2a

化简cos^2(A+15)+cos^2(A-15)-cos30cos2A 化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180)15为15度 化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].请大家解释一下.[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=1-2si 化简(sin a^2/cos a +cos a)*cot a 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) 化简 1-sin^4a-cos^4a/cos^2a-cos^4a 化简(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)== 化简:sin(-a)*cos(-a-兀)*tan(2兀+a) sin(180度+a)*cos(-a)/tan(-a) 化简 ：1+ 2cos^2 a - cos 2 a 化简：2cos(A+B)cosB-cos(2A+B) 2cos(π/2+a)cos(π-a)化简 化简cos(a+b)cos(a-b)+sin^2b 化简cos^2(派-A) 化简：cos^2A-1 化简cos^4 a-(1/4)cos^2 2a-(1/2)cos 2a 化简:cos^2A+cos^2(60°+A)+cos^2(60°-A) 化简cos^2A+cos^(120°+A)+cos^2(240°+A)这个怎么化简呢? cos^2A+cos^2(A+60)-cosA*cos(A+60) 化简