Chapter 11.3, Problem 34E

To determine

(a)

To prove:

For $\alpha \ne 0^{\circ }$, the identity $\cot \alpha =\frac{\cos \alpha }{\sin \alpha }$.

To determine

(b)

To show:

The trigonometric ratio $\cot {57}^{\circ }$ is equivalent to $\frac{\cos {57}^{\circ }}{\sin {57}^{\circ }}$ using calculator.