The graph in the accompanying figure shows the average Fahrenheit temperature in Fairbanks, Alaska, during a typical 365 -day year. The equation that approximates the temperature on day $x$ is
$$y=37 \sin \left[\frac{2 \pi}{365}(x-101)\right]+25$$
and is graphed in the accompanying figure.
a. On what day is the temperature increasing the fastest?
b. About how many degrees per day is the temperature increasing when it is increasing at its fastest?
(FIGURE CAN'T COPY).