函数fx=2asin²x-2√3asinxcosx+a+b,x属于(0,π/2)值域[-5,1],求a,b

问题描述:

函数fx=2asin²x-2√3asinxcosx+a+b,x属于(0,π/2)值域[-5,1],求a,b

2sin^2x=1-cos2x
2sinxcosx=sin2x
f(x)=a-acos2x-a√3sin2x+a+b
=2a+b-2a(cos2xcosπ/3+sin2xsinπ/3)
=2a+b-2acos(2x-π/3)
-5