about producing clear carrier signal

carrier_Fs=24e3;

Carrier_Fc=10e3;

no of samples: 240000..i have taken no samples for carrier signal becuase input signal is a audio signal which have 240000 samples..

while trying get the cosine wave using cos equation ..i am not getting the clear cos wave...i am getting distorted wave...

carrier=int32(Ac*32767*cos(2*pi*Fc*t/Fs));

here t value variese from 1:240000. and i am changing the double values into integer values...i don't think that conversion effects the wave form...