Question

(5-3sinx)/cosx 的最值

Answer 1

t=(5-3sinx)/cosx

tcosx=5-3sinx

tcosx+3sinx=5

√(t^2+3^2)sin(x+θ)=5

sin(x+θ)=5/√(t^2+9)

由三角函数有界性-1