Question

y=(1-sina)/cosa求值域：y=(1-sina)/cosa答案是y>2-√3题目只是我在做大题目时自己做到的一

Answer 1

=[sin²(a/2)-2sin(a/2)cos(a/2)+cos²(a/2)]/[sin²(a/2)-cos²(a/2)]

=[sin(a/2)-cos(a/2)]²/[cos(a/2)-sin(a/2)][cos(a/2)+sin(a/2)]

=[cos(a/2)-sin(a/2)]/[cos(a/2)+sin(a/2)]

=[1-tan(a/2)] / [1+tan(a/2)]

= -1 + 2 / [1+tan(a/2)]