`cos(A/2)=+-sqrt((1+cos A)/(2))`

Using the formula cos A =sqrt((1+cos2A)/(2)) , find the value of cos30^(@) , it is given that cos60^(@)=(1)/(2) .

cos^(-1)(sqrt((1+cos x)/2))

Show that : cos30^(@)=sqrt((1+cos60^(@))/(2))

Prove that cos^(-1) {sqrt((1 + x)/(2))} = (cos^(-1) x)/(2) , -1 lt x lt 1

Evaluate lim_(ntooo) n^(2){sqrt((1-"cos"(1)/(n))sqrt((1-"cos"(1)/(n))sqrt((1-"cos"(1)/(n))...)))} .

solve (cosA)/sqrt(1-cos^2A)

Prove that : 2 cos A = sqrt ([2 + sqrt (2 (1 + cos 4 A))]) , A in I or IV Quadrant.

Prove that : (1)/(2) cos^(-1) ((1+ 2 cos x)/( 2+cosx) ) = tan^(-1) ((1)/(sqrt(3)) "tan" (x)/(2))

Statement -1: if -1lexle1 then sin^(-1)(-x)=-sin^(-1)x and cos^(-1)(-x)=pi-cos^(-1)x Statement-2: If -1lexlex then cos^(-1)x=2sin^(-1)sqrt((1-x)/(2))= 2cos^(-1)sqrt((1+x)/(2))

if y=sqrt((1-cos x )/(2)) , the n prove that (dy)/(dx)=1/2cos" x/2.