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题目棱长为a的正四面体的体积是__. 解法1(公式法——用三棱锥体积公式) 如图1,∵四面体P-ABC是正四面体∴P在底面ABC的射影H是/△ABC中心.
The size of the regular tetrahedron with a rib length a is __. Solution 1 (formula method - using a triangular pyramid volume formula) As shown in Fig. 1, the tetrahedron P-ABC is a regular tetrahedron and the projection P on the bottom ABC is /△ ABC Center.