题目内容
如图所示.P为△ABC内任意一点,三边a,b,c的高分别为ha,hb,hc,且P到a,b,c的距离分别为ta,tb,tc.求证:
+
+
=1.
| ta |
| ha |
| tb |
| hb |
| tc |
| hc |
证明:连接AP、BP、CP.
根据三角形的面积公式,得
| ta |
| ha |
| S△BPC |
| S△ABC |
| tb |
| hb |
| S△APC |
| S△ABC |
| tc |
| hc |
| S△ABP |
| S△ABC |
∴
| ta |
| ha |
| tb |
| hb |
| tc |
| hc |
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