Formula's of S and S Posted by Soman Khan , Sunday, March 28, 2010 at 6:06 AM, in

Formulas written by sir Junaid in class of Signal and systems on Thursday,25th of March are written below

cos(X + Y) = cosX cosY - sinX sinY
cos(X - Y) = cosX cosY + sinX sinY
sin(X + Y) = sinX cosY + cosX sinY
sin(X - Y) = sinX cosY - cosX sinY 

cos ²X +sin ²X=1

cos(2X)= cos ²X -sin ²X
cos(2X) = 1 - 2sin ²X

cos(2X)= 2cos ²X - 1 

sin(2X) = 2 sinX cosX
sin ²X = (1 - cos(2X))/2
cos ²X =(1 + cos(2X))/2

sin(90-A)=cosA

cos(90-A)=sinA