sin(π/4 -α)=5/13,且α∈(0,π/2),则cos2α / cos(π/4 +α)=?sin(π/4 -α)=5/13,且α∈(0,π/2),则cos2α / cos(π/4 +α)=?

问题描述:

sin(π/4 -α)=5/13,且α∈(0,π/2),则cos2α / cos(π/4 +α)=?
sin(π/4 -α)=5/13,且α∈(0,π/2),则cos2α / cos(π/4 +α)=?