" (ii) "sin(70^(@)+theta)-cos(20^(@)-theta)=0

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)

Prove that :(sin theta cos(90^(0)-theta)cos theta)/(sin(90^(0)-theta))+(cos theta sin(90^(0)-theta)sin theta)/(cos(90^(@)-theta))=1csc^(2)(90^(@)-theta)-tan^(2)theta=cos^(2)(90^(@)-theta)+cos^(2)theta

Without using trigonometric tables,evaluate each of the following: (sin^(2)20^(@)+sin^(2)70^(@))/(cos^(2)20^(0)+cos^(2)70^(@))+(sin(90^(@)-theta)sin theta)/(tan theta)+(cos(90^(@)-theta)cos theta)/(cot theta)+cos(40^(0)+theta)-sin(50^(@)-theta)+(cos^(2)40^(0)+cos^(2)50^(@))/(sin^(2)40^(0)+sin^(2)50^(@))

sin theta -cos theta=0

(sin^(2) 20^(@) + sin^(2) 70^(@))/(cos^(2) 20^(@) + cos^(2) 70^(@)) + [ (sin (90^(@) - theta).sin theta)/(tan theta) + (cos (90^(@) - theta).cos theta)/(cot theta) ] .

If sin theta = cos (20^(@)+theta) , then theta is equal to :