MathDB
Order the Numbers

Source: 1994 National High School Mathematics League, Exam One, Problem 4

March 1, 2020

Problem Statement

0<b<1,0<a<π40<b<1,0<a<\frac{\pi}{4},x=(sina)logbsina,y=(cosa)logbcosa,z=(sina)logbcosax=(\sin a)^{\log_{b}\sin a},y=(\cos a)^{\log_{b}\cos a},z=(\sin a)^{\log_{b}\cos a}. Then the order of x,y,zx,y,z is (A)x<z<y(B)y<z<x(C)z<x<y(D)x<y<z\text{(A)}x<z<y\qquad\text{(B)}y<z<x\qquad\text{(C)}z<x<y\qquad\text{(D)}x<y<z