A trigonmetric integral. Please help

Hey if anyone could solve this integral for me it would be much appreciated:

Note: I have only done 3 unit mathematics (Australian HSC) and I don't start Integral calculus until Semester 2, so there are several integral properties I know nothing about. In fact I'm not sure if this can be solved (looking on wikipedia I was unable to find a formula):

(L^.5)dr

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L((mgcos(r/L))^.5)

This has the limits and the integration sign left out. I have left out the limits because I'm still working on defining them so if anyone who has the time to solve this can leave the integrated function in the form [f(x)] I'll know that I need to sub the limits in.

If the above is a little difficult to read, once constants (L, m and g) are taken out the integral is

dr/((cos(r/L))^.5) with the denominator being the square root of cos(r/L).

Thanks