<正> 94全国高中数学竞赛第二试三题:如图,设△ABC的外接圆O的半径为R,内心为I,∠B=60°,∠A<∠C,∠A的外角平分线交圆O于E,证明:(1)IO=AE;(2)2R<IO+IA+IC<(1+3~(1/2)R。
“在已知二次曲线上求一点,使它到两定点距离之和有最大或最小值”一类题,“光学性质”不仅于抛物线可用(这是大家熟知的),本文举例说明,对其他二次曲线也可用。
音乐教学中审美教育很重要,它是一种方式和手段,教师应该充分认识到其重要性。在教学中应培养审美情感、培养欣赏能力、培养感受能力、培养表现能力和创造能力。同时,音乐教
Although multiple-input multiple-output (MIMO) underwater acoustic (UWA) communication has been intensively investigated in the past years, existing works mainl
This paper explores a highly accurate identification modeling approach for the ship maneuvering motion with fullscale trial.A multi-innovation gradient iterativ
从分析师专美术专业欣赏课的主要问题入手,在阐述培养师范生审美能力意义的基础上,论述了高师美术专业欣赏课中培养师范生审美能力的主要途径：更新欣赏理念,增强学生的审美意
The modified suction caisson (MSC) is a novel type of foundation for ocean engineering, consisting of a short external closed-top cylinder-shaped structure surr
Hydroelastic effect of sloshing is studied through an experimental investigation.Different excitation frequencies are considered with low-fill-depth and large a
1992年全国高中联赛第二试第一题是: 设A<sub>1</sub>A<sub>2</sub>A<sub>3</sub>A<sub>4</sub>为⊙C的内接四边形,H<sub>1</sub>H<sub>2</sub>,H<sub>3</sub>,H<sub>4</sub>
定理若点P为正多面体外接球上任一点,则该正多面体各顶点到球的过P点的切面的距离之和为定值。事实上,设正多面体顶点为A<sub>1</sub>,…,A<sub>n</sub>（n=4,8,6,20,12）,外接球