21.sin^(2)40^(@)+sin^(2)50^(@)=1

Evaluate : (sec^(2)theta-cot^(2)(90^(@)-theta))/("cosec"^(2)67^(@)-tan^(2)23^(2))+(sin^(2)40^(@)+sin^(2)50^(@))

Evaluate : (sec^(2)theta-cot^(2)(90^(@)-theta))/("cosec"^(2)67^(@)-tan^(2)23^(2))+(sin^(2)40^(@)+sin^(2)50^(@))

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^(@))

Evaluate: sin^(2)40^(@)-cos^(2)50^(@)

Sin^(2)50^(@)+Sin^(2)70^(@)+Sin^(2)170^(@)=

4cos^(3)40^(@)-3sin50^(@)=

sin^(2)50^@+cos^(2)50^@=?

2 sin 40^(@) sin 10^(@)=

Show that sin10^(@)+sin20^(@)+sin40^(@)+sin50^(@) =sin70^(@)+sin80^(@)