解析 解直接计算,得r'(t)=(-asint,acost,b) ,r''(t)=(-acost,-asint,0) ,r'*r''=(absint,-abcost,a^2) .因此||r'|=√(a^2+b^2) | ||r'*r'|=a√(a^2+b^2)代入公式(4),得出曲率k=a/(a^2+b^2)它是一个常数,这与几何直觉是相符合的 ...
【内容导航】 Cost code-成本代码 【知识点】 Cost code-成本代码 Cost code-成本代码 Once the costs have been classified, a coding system can be applied to make it easier to manage the cost data. Each individual cost should be identifiable by its code. Features of a good coding system: •...
大一高数空间曲线的切线与法平面1、求曲线x=a×cost,y=a×sint,z=bt在t=90°处的切线和法平面方程.
BT Profit Jumps on Cost CutsLilly Vitorovich
BT has sold its stake in Distributed, the UK-based freelance startup as the telco giant continues to shave costs. A BT Group spokesperson confirmed toCapacitythat Distributed had been sold: “BT Group no longer holds a stake in the business, but we continue to use their elastic teams fo...
证明:螺旋线x = acost, y = asint, z = bt的切线与z轴形成定角。证明:螺旋线的切向量为.与z轴同向的单位向量为两向量的夹角余弦为为一定值。故螺旋线的切线与z轴形成定角。 答案 无相关推荐 1证明:螺旋线x = acost, y = asint, z = bt的切线与z轴形成定角。证明:螺旋线的切向量为.与z轴...
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清一色全部上这些厉害的武将，而普通玩家却只能用仅有的武将组合去抵抗一支 吕布 张飞 关羽 夏侯惇 赵云等等。所有厉害武将的BT组合。大致就是这样，三国志的COST值是可以随着你的等级提高而增加的。
1.求下列函数的拉普拉斯变换(1) f(t)=sint⋅cost ,(2) f(t)=e^(-4t) ,(3) f(t)=sin^2t(4) f(t)=t^2 ,(5)f(t)=sinhbt 相关知识点: 试题来源: 解析 解:(1)f(t)=sint⋅cost=1/2sin2tL(f(t))=1/2L(sin2t)=1/2⋅2/(s^2+4)=1/(s^2+4) 2)L(f(t))=1/...
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