角A+角B≤60°,证明sinA+sinB≤1
问题描述:
角A+角B≤60°,证明sinA+sinB≤1
答
证明:∵∠A+∠B=60º∴∠B=60º-∠AsinA+sinB=sinA+sin(60º-A)=sinA+sin60ºcosA-cos60ºsinA=sinA+√3/2*cosA-1/2*sinA=√3/2*cosA+1/2*sinA=sin60ºcosA+cos60ºsinA=sin(60º+...