1-cost等于多少

蓟胀魏1232 - ∫cottdt为什么=1/sint -
池沸邓13016259152 ______ -∫cottdt=-∫cost/sint dt=-∫1/sintdsint=-ln|sint|+c

蓟胀魏1232利用等价无穷小的代换性质求,当x趋于1时,(1+cosπx)/(x - 1)^2的极限是多少...拜托... -
池沸邓13016259152 ______ 令x-1=t,则 当x趋于1时,t趋于0 (1+cosπx)/(x-1)^2 =(1+cosπ(t+1))/t^2 =(1-cost)/t^2 1-cost等价于t^2/2 所以 原式的极限=1/2.

蓟胀魏1232三角函数cos2t如何变形成1 - cost^2 -
池沸邓13016259152 ______ cos2t=cos(t+t)=costcost-sintsint=cos^2t-sin^2t=cos^2t-(1-cos^2t)=2cos^2t-1 (cos^2t=(cost)平方)

蓟胀魏1232为什么sint/(1 - cost)=cot(t/2) -
池沸邓13016259152 ______[答案] sint = 2sin(t/2)cos(t/2) 1-cost = 1-(1-2sin²(t/2))=2sin²(t/2) 所以 sint/(1-cost)=2sin(t/2)cos(t/2)/2sin²(t/2)=cos(t/2)/sin(t/2)=cot(t/2)

蓟胀魏1232sint/1 - cot怎么得cott/2是1 - cost -
池沸邓13016259152 ______[答案] 解 sint/(1-cost) =(2sint/2cost/2)/(2sin²t/2) =(cost/2)/(sint/2) =cott/2

蓟胀魏1232cost(1 - cost) - sintsint化简 -
池沸邓13016259152 ______ cost(1-cost)-sint.sint =cost - [ (cost)^2 + (sint)^2 ] =cost -1

蓟胀魏1232求下列参数方程所确定函数的二阶导数:x=a(t - sint),y=a(1 - cost) -
池沸邓13016259152 ______ dx/dt=a(1-cost) dy/dt=asint y'=sint/(1-cost) dy'/dt=[cost(1-cost)-sint*sint]/(1-cost)^2=(cost-1)/(1-cost)^2=-1/(1-cost) y＂=(dy'/dt)/(dx/dt)=-1/[a(1-cost)^2]

蓟胀魏1232高数 求弧长 参数方程 x=a(t - sint) y=a(1 - cost) t[0,2π] -
池沸邓13016259152 ______[答案] dx/dt=a(1-cost),dy/dt=asint 由公式: 弧长S=∫√[(dx/dt)^2+(dy/dt)^2] dt 积分从0到2π =∫√a^2[1-2cost+(cost)^2]+(asint)^2] dt =a∫√(2-2cost) dt =a∫2|sin(t/2)| dt =8πa

蓟胀魏1232x=1/cost求dx等于多少怎么算 -
池沸邓13016259152 ______ dx=-(cost)^(-2)*(-sint)dt=(cost)^(-2)*sint*dt=sint/(1-sint)*dt 如果愿意的话可以继续转化为=(1/(1-sint)-1/(1+sint))/2*dt 看你自己喜欢了.

蓟胀魏1232t趋向于0+,lim(1 - cost)/t是多少? -
池沸邓13016259152 ______[答案] 1-cost趋向于 t²/2 所以lim(1-cost)/t=lim t/2 =0