(a) (14 points) Use trigonometric identities to find all trigonometric function values of a. \text { 4. ( } 20 \text { points) Suppose that } \sec (\alpha)=-\frac{5}{\sqrt{5}} \text {

and } \alpha \text { is on the third quadrant. } \text { (b) ( } 6 \text { points) Find all trigonometric function values of } \beta=-\alpha \text { . }