Help!: int(expr,var) function returns the int(expr,var) function

When i try to make a fucntion described by two indefinite integrals, one of the indefinite integrals returns without being solved.

The variable x an angle between 0 and pi/2.

F_1 is a force.

R_1 and R_2 are lenghts.

%% Variables
syms x;
F_1 = 200; %N
R_1 = 30; % mm


L = 40; % mm
H = 20; % mm
R_2 = 20*(4*cos(x)^2 + sin(x)^2)^(1/2);


%% Equations
m_1(x)= F_1*sin(x)*R_1;
md_1(x)=sin(x)*R_1;

m_2(x)=F_1*R_2*cos(x);
md_2(x)=R_2*cos(x);


ex_1=R_1*m_1(x)*md_1(x);
ex_2=simplify(R_2*m_2(x)*md_2(x))
%% Integration
f(x)=int(ex_1,x) + int(ex_2,x)

f(x) =

2700000*x - 1350000*sin(2*x) - int(1600000*(4 - 3*sin(x)^2)^(3/2)*(sin(x)^2 - 1), x) - It should solve this one, but indstead it just spit out int(expresion,var) just as it was inserted.

Answer 1

[Cris LaPierre]

That likely means it couldn't solve that one.

Consider using one of the techniques mentioned in these two examples.

• Unevaluated Integral and Integration by Parts
• Approximate Indefinite Integrals

[Daniel Møgelbjerg]

We did it a little different, after realizing that our R_2 in fact was not a variable depending on x, but just another constant value. We are sorry for the eventually wasted time, but thanks a lot for the help.