已知P为三角形ABC内任意一点.求证:
1/2(AB+BC+CA)CA,PA+PB>AB,三式相加得:
2(PA+PB+PC)>AB+BC+CA PA+PB+PC>(AB+BC+CA)/2.
因为AB+AC>PB+PC,BC+AB>PC+PA,AC+BC>PA+PB,三式相加得:
AB+BC+CA>PA+PB+PC.
已知P为三角形ABC内任意一点.求证:
1/2(AB+BC+CA)CA,PA+PB>AB,三式相加得:
2(PA+PB+PC)>AB+BC+CA PA+PB+PC>(AB+BC+CA)/2.
因为AB+AC>PB+PC,BC+AB>PC+PA,AC+BC>PA+PB,三式相加得:
AB+BC+CA>PA+PB+PC.