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)

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：[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 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cos^2(A+15)+cos^2(A-15)-cos30cos2A 化简 ：1+ 2cos^2 a - cos 2 a 化简：cos^2A-1 化简:根号(1+cos a)/根号(1-cos a)+根号(1-cos a)/根号(1+cos a) 化简cos^4 a-(1/4)cos^2 2a-(1/2)cos 2a 化简1+cos(a-360)cos（a-180）-2cos^2a 化简sin(a-15度)cos（a+15度）+cos（a-15度)sin(a+15度) 化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180)15为15度 化简1：cos(15°-a)sin15°-sin(165°+a)cos(-15°)2：根号下cos(60°-a)-sin(60°-a) 化简tan a(cos a-sin a)+sin a(sin a+tan a)/1+cos a 化简 （1+sin a+ cos a)(sin a/2 - cos a/2) / √(2+2cos a)(180° sin(a+105度)cos(a-15度)-cos(a+105度)sin(a-15度) 化简1-sin^4a-cos^4a/1-sin^6a-cos^6a 1-sin^6a-cos^6a分之1-sin^4a-cos^4a 化简