设人的身高H=1.7m,人和地平线之间所对应的地球的圆心角a人到地平线之间的距离L而地球半径R=6400km则:H=(R/cosa)-RH=R(1-cosa)/cosa=R*2(sin(a/2))^2/cosa≈R*2(a/2)^2=Ra^2/2a^2=2H/RL=R*a=R*(2H/R)^(1/2)=(2HR)^(1/...