## Fsk demodulation

Hey somebody can help me please to understand how they arrive to this solve of correlation rks,rkc. It is from a fsk demodulation algorithm they do 2 Integration, one time between sin(2*pi*fc*t+2pi*m*deltaf*t)*cos(2*pi*fc*t+2pi*m*deltaf*t+phase) and seconed time between cos(2*pi*fc*t+2pi*m*deltaf*t)*cos(2*pi*fc*t+2pi*m*deltaf*t+phase) but I doesnt understand how they solve this integral (7.5.11)

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