[" How in the first quadrant and "cos x=(8)/(17)" ,then prove that "],[cos((pi)/(6)+x)+cos((pi)/(4)-x)+cos((2 pi)/(3)-x)=((sqrt(3)-1)/(2)+(1)/(sqrt(2)))(23)/(17)" (NCERTERFR "]

If theta lies in the first quadrant and cos theta=(8)/(17), then prove that cos((pi)/(6)+theta)+cos((pi)/(4)-theta)+cos((2 pi)/(3)-theta)=((sqrt(3)-1)/(2)+(1)/(sqrt(2)))(23)/(17)

If theta lies in the first quadrant and costheta=8/(17) , then prove that cos(pi/6+theta)+cos(pi/4-theta)+cos((2pi)/3-theta)=((sqrt(3)-1)/2+1/(sqrt(2)))(23)/(17)

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

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

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

Prove that cos ((pi)/(4) + x) + cos ((pi)/(4) -x) = sqrt2 cos x

Prove that cos ((pi)/(4) + x) + cos ((pi)/(4) -x) = sqrt2 cos x

Prove that cos ((pi)/(4) + x) + cos ((pi)/(4) -x) = sqrt2 cos x

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