`cos(pi/4-A)-sin(pi/4+A)=0`

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

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

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

sin(pi/4+A).sin(pi/4-A)=1/2 cos2A

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

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

Evaluate the following: (cos(2 pi))/(3)(cos pi)/(4)-(sin(2 pi))/(3)(sin pi)/(4)

Using application of trignometric formulas prove that (i)cos(pi/4+x)+cos(pi/4-x)=sqrt2cos x(i1)sin(7pi/12)cos(pi/4)-cos(7pi/12)sin(pi/4)

The least positive integer n such that [{:(cos""(pi)/(4), sin""(pi)/(4)) ,(- sin ""(pi)/(4) , cos ""(pi)/(4)):}]^(n) is an identity matrix of order 2 is