Prove that `cos(pi/4+x)+cos(pi/4-x)=sqrt(2)cosx`.

Prove that: cos(pi/4+A)+cos(pi/4-A)=sqrt(2)cosA

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)

Prove that: cos((pi)/(4)+x)+cos((pi)/(4)-x)=sqrt(2)cos x

Prove that: cos((pi)/(4)+x)+cos((pi)/(4)-x)=sqrt(2)cos x

cos((3pi)/(4)+x)-cos((3pi)/(4)-x) = -sqrt(2)sinx

Prove that quad cos((pi)/(4)+x)+cos((pi)/(4)-x)=sqrt(2)cos x

prove that sin((pi)/(4)+x)+sin((pi)/(4)-x)=sqrt(2)cos x

Prove that cos((pi)/(4)-x)cos((pi)/(4)+x)=(1)/(2)-sin^(2)x

Prove that: cos((3 pi)/(4)+x)-cos((3 pi)/(4)-x)=sqrt(2)sin x

Prove that: cos((3 pi)/(4)+x)-cos((3 pi)/(4)-x)=-sqrt(2)sin x