" formula,"cos A=sqrt((1+cos2A)/(2))

Using the formula, sinA=sqrt((1-cos2A)/(2)) , find the value of sin30^(@) , it being given that cos60^(@)=(1)/(2) .

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

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

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

If cos A = sqrt((sqrt(2)+1)/(2sqrt(2))) , find the value of cos2A

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

tan ""A/2 is equal to.............. A) sqrt((1- sin A)/( 1+ sin A)) B) sqrt((1+ sin A)/(1- sin A)) C) sqrt((1 -cos A)/(1 + cos A)) D) sqrt((1 +cos A)/(1- cos A))

cos 15^(@) =............. A) sqrt((1+cos 30^(@))/(2)) B) sqrt((1-cos 30^(@))/(2)) C) pm sqrt((1+cos 30^(@))/(2)) D) pm sqrt((1- cos30^(@))/(2))

In the formula 2cos((A)/(2))=+-sqrt(1+sin A)+-sqrt(1-sin A) if two positive signs are taken