由三角形三边表示面积的海伦公式的常见证法一般都较冗繁,它往往需要添置辅助线,而且涉及的知识和运算也较多.本文拟给出一个简证,它只用到少许的知识和运算即可.证明:设△ABC 三内角 A、B、C 所对的边分 The common proof of Helen’s formula for the area represented by three sides of the triangle is generally more tedious. It often requires the addition of auxiliary lines, and it involves more knowledge and operations. This paper proposes a simple proof, it only uses a little knowledge The sum operation is enough. Proof: Let ΔABC be the edge of the three inner angles A, B, C.