ldcf.net
輝念了崔遍匈 >> 箔屬tAnx+2Cot2x=Cotx >>

箔屬tAnx+2Cot2x=Cotx

cot2x=1/tan2x=(1-tan²x)/2tanx 2cot2x=(1-tan²x)/tanx=1/tanx-tanx=cotx-tanx tanx+2cot2x=cotx 屬穎

恣円=cos^2x/sin^2x -cos^2x =cos^2x/sin^2 (1-sin^2x) =cot^2x cos^2x

嗾擬巷塀 tan(π/2-x)=cotx cot2x=1/tan2x=1/[2tanx/(1-tan²x)] =(1-tan²x)/(2tanx) =(1-1/cot²x)/(2/cotx) =[(cot²x-1)/cot²x]/(2/cotx) =(cot²x-1)/(2cotx)

×1+tanx+cotx=1+tanx+1/tanx=(tanx+tan^2x+1)/tanx ÷1+tanx+cotx/1+tan^2x+tanx)=1/tanx ×cotx/(1+tan^2x)=cotx/(tanxcotx+tan^2x)=cotx/(tanx(cotx+tanx)) ÷圻塀=1/tanx-cot/tanx(tanx+cotx)=1/(tanx+cotx)

〈(cotx)^6dx =〈(csc^2x-1)cot^4xdx =〈csc^2xcot^4xdx-〈cot^4xdx =-〈cot^4xdcotx-〈(csc^2x-1)cot^2xdx =-cot^5x/5-〈csc^2xcot^2xdx-〈cot^2xdx =-cot^5x/5+cot^3x/3-cotx+x+C

〈 x*csc^2x*cot^2x dx =(1/3)*〈 x*(3*csc^2x*cot^2x) dx =(1/3)*〈 x d(cot^3x) ´´鑑裏蛍隈 =(1/3)*x*cot^3x - (1/3)*〈 cot^3x dx ´´蛍何持蛍隈 =(1/3)*x*cot^3x - (1/3)*〈 cos^3x/sin^3x dx =(1/3)*x*cot^3x - (1/3)*〈 cos^2x/sin^3x d(sinx) ´´...

利嫋遍匈 | 利嫋仇夕
All rights reserved Powered by www.ldcf.net
copyright ©right 2010-2021。
坪否栖徭利大泌嗤盃係萩選狼人捲。zhit325@qq.com