Introduction to...

If $$A$$ and $$B$$ are complementary angles, then $$\sin A \times \sec B =$$

$$\cot (90 - \theta) = $$

If $$A$$ and $$B$$ are acute angle such that $$\sin A = \cos B$$, then $$(A + B) = .....$$

If $$\cos 9\alpha = \sin \alpha$$, and $$9\alpha < 90^{\circ}$$, then $$\tan 5\alpha = .....$$

$$\tan (90 - \theta) $$ is equivalent to 

$$\cot (90^{\circ} - \theta) $$ is equivalent to

$$\csc (90 - \theta) = $$ is equivalent to

$$\sin^{2} 20^{\circ} + \sin^{2} 70^\circ=$$?

Evaluate: $$\dfrac {\tan 35^{\circ}}{\cot 55^{\circ}} + \dfrac {\cot 78^{\circ}}{\tan 12^{\circ}} = $$

If $$\sin 15^{\circ} = \cos (n\times15^{\circ})$$, then $$n = .....$$