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在平时的解题活动中,注重反思总结,善于从特殊的个案中觉察规律,提出猜想,通过检验、证明等一系列科学方法,往往可得意外收获,提炼出更一般的规律. 1 预备知识 (1)三角形周长为p,面积为S,则内切圆半径2/rSp=. (2)棱锥的全面积为S,体积为V,则内切球半径3/rVS=. (3)正n边形内切圆
In the usual problem-solving activities, they focus on reflection and summarization, are good at perceiving the laws from particular cases, and come up with conjectures. Through a series of scientific methods such as examination and proof, they often receive unexpected gains and refine more general laws. (1) The perimeter of the triangle is p, and the area is S. Then the radius of the inscribed circle is 2/rSp=. (2) The total area of the pyramid is S, and the volume is V, then the radius of the inscribed sphere is 3/rVS=. (3) Positive n-shaped inscribed circle