" 6."cos((pi)/(4)-x)cos((pi)/(4)-y)-sin((pi)/(4)-x)sin((pi)/(4)-y)=sin(x+y)

Prove that cos((pi)/(4)-x)cos((pi)/(4)-y)-sin((pi)/(4)-x)sin((pi)/(4)-y)=sin(x+y)

Prove that: cos((pi)/(4)-x)cos((pi)/(4)-y)-sin((pi)/(4)-x)sin((pi)/(4)-y)=sin(x+y)

Prove cos ((pi)/(4) - x) cos ((pi)/(4) -y) - sin ((pi)/(4) -x) sin ((pi)/(4) -y) = sin ( x +y)

Cos((pi)/(4)+A).Cos((pi)/(4)-B)-Sin((pi)/(4)+A).Sin((pi)/(4)-B)=

Prove the following: cos(pi/4-x)cos(pi/4-y)-sin(pi/4-x)sin(pi/4-y)= sin (x+ y)

Prove the following: cos(pi/4-x).cos(pi/4-y)-sin(pi/4-x).sin(pi/4-y)=sin(x+y)

Prove that: cos(pi/4-x)cos(pi/4-y)-sin(pi/4-x)sin(pi/4-y)=sin(x+y)

Prove the following cos ((pi) / (4) -x) cos ((pi) / (4) -y) -sin ((pi) / (4) -x) sin ((pi) / (4) - y) = sin (x + y)

cos((pi)/(4)+A) cos((pi)/(4) - B) + sin ((pi)/(4) +A) * sin((pi)/4-B)=

Prove that cos(pi/4-x)cos(pi/4-y)-sin(pi/4-x)sin(pi/4-y)=sin(x+y)