Question

已知函数f(X)=(sin2x+cos2x+1)/2cosx,求函数值域

Answer 1

先化简
f(x)
=(sin2x+cos2x+1)/2cosx
=(2sinxcosx+2(cosx)^2-1+1)/(2cosx)
=sinx+cosx
=√2(√2/2sinx+√2/2cosx)
=√2(sinxcosπ/4+sinπ/4cosx)
=√2sin(x+π/4)
-1