4.9-1/化簡：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)]._知道
提問者採納: [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...
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