在三角形ABC中 角C+角A=2角B 角C-角A=80度,求角A=20度角B=60度角C=100度
角A40度,角B60度,角C80度
角A 20°角B 60°角C 100°
A20B60C100
c + a = 2bc - a = 80-->c = a+80,带入1--> a + 80 + a = 2b a + 40 = ba + b + c =180== a +80 + a + 40 + a =180 ---a = 20,b = 60 c =100