restart;
# Work a complicated antiderivative related to surface area
f := tan(x);

dfdx := diff(f, x);

P := int(f*sqrt(1+dfdx^2), x);

F2 := diff(P, x);


simplify(F2);

F3:=tan(x)*sqrt(1+sec(x)^4);

simplify(F2-F3);

F:=unapply(P,x);

A1:=F(2*Pi/5)-F(Pi/7);

simplify(A1);

evalf(A1);

Digits:=100;

evalf(A1);

restart;
# Find an antiderivative
int(ln(x)^2,x);

restart;
# Work an arc length problem
f:=y^3/21+7/(4*y);
dfdy:=diff(f,y);


int(sqrt(dfdy^2+1),y=3..5);