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)=

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

cos((3pi)/4+x)-sin(pi/4-x)=?

Prove the following: cos(pi/2-x)cos(pi/2-y)-sin(pi/2-x)sin(pi/2-y)=-cos(x+y)

Statement -1 The value of determinant |{:(sinpi,cos(x+(pi)/(4)),tan(-(pi)/(4))),(sin(x-(pi)/(4)),-cos((pi)/(2)),In((x)/(y))),(cot((pi)/(4)+x),In((y)/(x)),tan(pi)):}| is zero Statement -2 The value of skew -symetric determinat of odd order equals zero.

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

What is the value of cos(pi/4-x)cos(pi/4-y)-sin(pi/4-x)sin(pi/4-y)?

If x=sin((pi)/(3)+A)*cos((pi)/(3)+B) and y=cos((pi)/(3)+A)*sin ((pi)/(3)+B) then x-y=