[" ib "cos20=1-2sin^(2)theta],[" find ralue of "2" in "30^(@)" ."]

Using the formula cos 2theta = 2 cos^(2)theta - 1 , find the value of cos 30^(@) , it is being given that cos 60^(@) = 1/2

if sin^2theta=1/2 ,then find cos^2theta .

If sin theta = cos theta find the value of : 3 tan ^(2) theta+ 2 sin ^(2) theta -1

Prove that (i) " sin " (50^(@) + theta ) " cos " (20^(@) + theta) - " cos " (50^(@) + theta) " sin " (20^(@) + theta) =(1)/(2) (ii) " cos " (70^(@) + theta ) " cos " (10^(@) + theta ) + " sin " (70^(@) + theta) " sin " (10^(@) + theta)=(1)/(2)

If (2 sin theta )/(1+ cos theta + sin theta )=x, find the value of (1- cos theta + sin theta )/(1+ sin theta )

If sin theta = 12/13 (0^(@) lt theta lt 90^(@)) , find the value of (sin^(2) theta - cos^(2)theta)/(2 sin theta cos theta) xx (1)/(tan^(2)theta) .

If cos (20° + theta) = sin 30°, then find the value of theta.

If sin(20^(@)+theta)=cos30^(@) then find the value of theta .

Evaluate 2(cos^2theta-sin^2theta)=1

Prove that (sin 3 theta)/(1+2cos2 theta)=sin theta and hence find sin15^(@)