sin18*cos36=?
问题描述:
sin18*cos36=?
答
sin18*cos36=sin18*cos18*cos36/cos18=sin36*cos36/2cos18=sin72/4cos18=cos18/4cos18=1/4
sin18*cos36=?
sin18*cos36=sin18*cos18*cos36/cos18=sin36*cos36/2cos18=sin72/4cos18=cos18/4cos18=1/4