# Integrate() does not integrate

Good Evening

When I ask sage:

```
var('phi r')
phi1 = 0
phi2 = 2*pi
r1 = 3
r2 = 5
fpolar = - sqrt(-2*r^2*cos(phi)^2+25)
BI = fpolar
BI= integral(BI, (phi,phi1,phi2))
BI= integral(BI, (r,r1,r2))
BI
```

the result is:

```
-integrate(integrate(sqrt(-2*r^2*cos(phi)^2 + 25), phi, 0, 2*pi), r, 3,
5)
```

I've found no way to make sage integrate the expresion. It repeats my input and iam not given any *new* information.

When i try

```
BI.n()
```

i get

```
ValueError: Integrand has wrong number of parameters
```

Same Problem with indefinite Integrals

in:

```
BI = fpolar
BI= integral(BI, phi)
BI
```

out:

```
-integrate(sqrt(-2*r^2*cos(phi)^2 + 25), phi)
```

Why? what do I need to do to get the desired output?

I want to do things symbolic. When i did it in maple yesterday, it gave me nonsense. If even $$$ got Problems with such an equation, maybe it should be an feature request. Unfortuantly iam just a student of mechanical engineering, so i cant jugdge this situation. (Is it my fault or the CAS's, i suspect mine) I,however, can do it with my own sweat and tears. Thank you so far. UPDATE: Wolfram Mathematica semms to be unable to do it (at least when you go the simple way and just tell it to Integrate)