# The correct formula for the Fourier sine series appearing in

The correct formula for the Fourier sine series appearing in the solution of thin airfoil theory is_____

A. An=$$\frac {2}{\pi }\int_0^{\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅

B. An=$$\frac {1}{\pi }\int_0^{\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅

C. An=$$\frac {2}{\pi }\int_0^{2\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅

D. An=α-$$\frac {1}{\pi }\int_0^{\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅

The correct answer is A. An=$$\frac {2}{\pi }\int_0^{\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅
The explanation is: From the general solution of thin airfoil theory we have An=$$\frac {2}{\pi }\int_0^{\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅ and A0=α-$$\frac {1}{\pi }\int_0^{\pi }\frac {dz}{dx}$$ cos⁡n∅ d∅ where the limits are 0&leq;∅&leq;π.