Question

√3 sinxcosx+cos2x如何化简

补充一下cos2x是cosx的平方
我不会打

Answer 1

原式=√3/2*sin2x+(1+cos2x)/2
=√3/2*sin2x+1/2*cos2x+1/2
=sin2xcosπ/6+cos2xsinπ/6+1/2
=sin(2x+π/6)+1/2

Answer 2

a+b=3
两边平方
a^2+2ab+b^2=9
a^2+b^2=9-2ab=5
(a-b)^2=a^2-2ab+b^2=5-4=1
所以a-b=-1或1

所以a^2-b^2
=(a+b)(a-b)
=-3或3