9. Identify the vertex of the graph. Tell whether it is a minimum or maximum.

A. (–2, 1); minimum

B. (–2, 1); maximum

C. (1, –2); minimum

D. (1, –2); maximum

C. (1, –2); minimum

Step-by-step explanation:

D

Step-by-step explanation:

The vertex is the turning point of the graph.

This is at (- 1, - 2)

The graph changes from decreasing to increasing at (- 1, - 2)

Hence is a minimum at (- 1, - 2)

f(t) =  -2 cos 2t

Step-by-step explanation:

If we start with cos t then transform to - cos t we get a reflection in the t axis and the maximum  on the y axis will become a minimum.

Multiplying by 2 to give -2 cos t will stretch  the peaks from t = 1 and -1 to t = 2 and -2.

Finally  converting to  -2 cos 2t stretches the curve horizontally by a factor of 1/2. ( 'Squashing' it).