Question

三角函数问题请问这个tanξ/2是怎么得出来的?

Answer 1

的确不对：

cosa/(1-sina)=(cos^2(a/2)-sin^2(a/2))/(cos^2(a/2)-2sin(a/2)cos(a/2)+sin^2(a/2)))

=(cos(a/2)+sin(a/2))(cos(a/2)-sin(a/2))/(cos(a/2)-sin(a/2))^2

=(cos(a/2)+sin(a/2))/(cos(a/2)-sin(a/2))=(1+tan(a/2))/(1-tan(a/2))=2/(π-2)

故：tan(a/2)=(4-π)/π