求积分sqrt(1+x^2)最好别用sinh cosh等等谢

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求积分sqrt(1+x^2)最好别用sinhcosh等等谢求积分sqrt(1+x^2)最好别用sinhcosh等等谢求积分sqrt(1+x^2)最好别用sinhcosh等等谢令x=tan(t)dx=1

求积分sqrt(1+x^2)最好别用sinh cosh等等谢
求积分sqrt(1+x^2)
最好别用sinh cosh等等

求积分sqrt(1+x^2)最好别用sinh cosh等等谢
令x=tan(t)
dx=1/cos^2(t)dt
积分sqrt(1+x^2)dx
=积分1/cos^3(t)dt
=积分1/cos^4(t)d(sin(t))
=积分1/(1-sin^2(t))^2d(sin(t))
=1/4(ln(sin(t)+1)-1/(sin(t)+1)-ln(sin(t)-1)-1/(sin(t)-1))+C
再将sin(t)=1/(1+1/x^2)^0.5代入得
积分sqrt(1+x^2)=1/2*x*(1+x^2)^(1/2)+1/2*arcsinh(x)+C