1/cos50°+tg10°=1/sin40°+sin10°/cos10°=1/sin40°+(sin10°*2sin10°)/(cos10°*2sin10°)=1/sin40°+2(sin10°)^2/sin20°=1/sin40°+(1-cos20°)/sin20°=1/sin40°+(1-cos20°)*2cos20°/sin20°*2cos20°=[1+2cos20°-2(cos20°)^2]/sin40°=(2cos20°-cos40°)/sin40°=(cos20°+2sin30°sin10°)/sin40°=(sin70°+sin10°)/sin40°=[sin(40°+30°)+sin(40°-30°)]/sin40°=2sin40°cos30°/sin40°=2cos30°=√3
1/cos50度+tan10度等于多少？急急急！谢谢！
