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第77章 异面直线与共面圆(第1页)

章节目录保存书签

九月的风卷着香樟叶掠过窗沿时,沈砚之正在草稿纸上构建第三个正西面体模型。笔尖在纸面划出利落的折线,将空间分割成八个全等的卦限,最后一道斜线收笔时,前排忽然传来铅笔盒坠地的脆响。

“苏敛,”数学老师敲了敲黑板,“你来说说这道椭圆题的参数方程解法。”

被点名的少年转过来时,额前碎发还沾着阳光的金芒。他漫不经心地捡起笔,视线扫过投影幕布的瞬间,指尖己经在黑板上列出离心率公式:“设参数θ的话,x=acosθ,y=bsinθ,代入首线方程求判别式……”粉笔灰簌簌落在他校服口袋露出的半截竞赛准考证上,沈砚之瞥见那上面“圆锥曲线专项”的字样,不动声色地用橡皮擦掉了草稿纸上多余的辅助线。

后排突然传来翻书声。陆明野把《数学分析》摊在桌面上,荧光笔在拉格朗日中值定理旁画出波浪线。他的手指在微分符号?上顿了顿,抬眼时正好撞上苏敛投来的目光。两个同样耀眼的少年在空气里交换了一记无声的较量,像两条斜率不同的切线,在某一点短暂相交后便奔向各自的极值点。

这是A大附中理科实验班的日常。沈砚之的立体几何草稿纸永远整洁如建筑蓝图,苏敛演算圆锥曲线的步骤里总藏着剑走偏锋的巧思,而陆明野解导数题时,草稿纸上的函数图像永远像心电图般起伏剧烈。他们是年级公示栏上永远霸占前三名的名字,也是办公室里老师口中“可惜凑不到一起”的遗憾——沈砚之嫌苏敛的解法“不够严谨”,苏敛笑沈砚之“不懂变通”,陆明野则觉得前两者都“沉溺于具象而忽略了数学的本质”。

第一次真正意义上的交锋发生在十月竞赛集训营。当带队老师宣布三人将组成小组参加建模大赛时,沈砚之正在调试3D打印的空间模型,苏敛转笔的动作骤然停住,陆明野合上笔记本的声音在寂静的活动室里格外清晰。

“我的方案是用空间坐标系模拟建筑应力分布。”沈砚之率先打破沉默,将打印好的模型推到桌中央,透明亚克力材质的正十二面体在灯光下折射出冷硬的光,“所有数据可以通过立体几何转化为可量化的参数。”

苏敛嗤笑一声,摊开画满椭圆的草稿纸:“建筑外立面的弧形结构用圆锥曲线拟合更精准,你那些棱角分明的模型,算得清风荷载在曲面的分力吗?”

“两位都在讨论表象。”陆明野忽然开口,指尖点在笔记本的导数公式上,“结构稳定性的核心是动态变化率,风压、温度、湿度的微小改变都可能引发连锁反应,你们的静态模型不过是纸上谈兵。”

争吵最终以苏敛的铅笔戳穿草稿纸告终。那天傍晚,沈砚之对着模型里歪斜的支撑梁发呆,发现自己竟下意识地用了苏敛提过的椭圆曲线调整角度;苏敛在食堂排队时,脑子里反复演算着陆明野说的变化率,把餐盘里的排骨都当成了函数图像上的拐点;陆明野走在回宿舍的路上,抬头看见教学楼的玻璃幕墙在暮色里切割出立体几何的轮廓,忽然想起沈砚之模型里那些严丝合缝的角度。

集训营的第二周,台风过境的夜晚让实验室断了电。应急灯亮起时,三人正围着短路的电脑发愁——沈砚之设计的空间模型文件损坏,苏敛的曲线参数丢失,唯有陆明野的导数分析还存在U盘里。

“用我的备用数据吧。”沈砚之从抽屉里翻出U盘,里面是他按不同角度备份的模型参数,“虽然麻烦点,但可以重建坐标系。”

苏敛忽然笑了,从笔记本里抽出一张纸:“我昨天顺手把曲线方程转换成了参数形式,或许能和你的坐标系对接。”

陆明野没说话,只是默默打开自己的文件,将变化率公式拆解成更基础的微分形式。应急灯的光晕里,沈砚之的笔尖在空间坐标轴上跳跃,苏敛的曲线在坐标系里逐渐舒展,陆明野的导数公式像无形的纽带,将静态的结构与动态的变化串联起来。当屏幕重新亮起,三者融合的模型在虚拟空间里旋转时,窗外的台风似乎都温柔了许多。

章节目录

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