正三棱锥是最常见的几何体,棱的中点常在解题中起着重要作用.如何设置中点,如何利用中点?本文试图对此予以浅析.先熟悉正三棱锥的常见性质.正三棱锥除了一般正棱锥所具有的性质外,还有以下特有的性质(证明从略):图1性质图1.三组相对棱互相垂直,如图1中AB⊥PC,底面的棱垂直于过? The regular triangular pyramid is the most common geometry. The midpoint of the edge often plays an important role in solving the problem. How to set the midpoint and how to use the midpoint? This paper attempts to analyze this. First, familiar with the common properties of the regular triangular pyramid. In addition to the general characteristics of regular pyramids, there are also the following unique properties (proof is omitted): Figure 1 Properties Figure 1. The three groups of relative edges are perpendicular to each other, as in Figure 1 AB ⊥ PC, the bottom of the rib perpendicular to the over?