我这边有结果阿.
>> syms x; int(sqrt(1+pi^2*cos(x).^2),0,2);
>> y=int(sqrt(1+pi^2*cos(x).^2),0,2)
y=
1/8388608*3059521645650671^(1/2)*EllipticE(1/3059521645650671*8499493916249719503250543500065^(1/2))-1/16777216*3059521645650671^(1/2)*EllipticE((1-cos(2)^2)^(1/2),1/3059521645650671*8499493916249719503250543500065^(1/2))
>> y=double(y)
y =
4.1539
>>
追问额,不是吧
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