For an acute angle A, sin A = 0.6. Find cos A, tan A and sec A.

The identities: $\sin^2 A + \cos^2 A = 1$, $1 + \tan^2 A = \sec^2 A$ and $1 + \cot^2 A = \text{cosec}^2 A$. For an acute angle, every ratio is positive, so take the positive square root.