在数学中有不等式的恒成立问题:(1)不等式f(x)≥C对任意x∈[a,b]恒成立f(x)min≥C;(2)不等式f(x)≤C对任意x∈[a,b]恒成立f(x)max≤C.这2个结论在物理问题中也有着广泛应用,现举例说明这类问题的解题策略.例1.如图1所示,用透明材料做成一长方体光学器材,要求从上表面射入的任意光线(即入射角θ为任何值) (1) The inequality f (x) ≥C holds for any x∈ [a, b], and f (x) min≥C. (2) The inequality f Arbitrary x∈ [a, b] constant holds f (x) max≤C. These two conclusions are also widely used in physics problems, and illustrate the problem-solving strategies for such problems. , With a transparent material made of a rectangular optical instrument, requiring any light incident from the upper surface (ie, the incident angle θ is any value)