There is no rate of change of Function 1. It's slope(rate of change) is zero.
Function 2 has a slope of 2.
The complimentary event is the probability of it not raining. The probability of that is 1-2/5 = 3/5.
A theorem states that, given a circle with center C and a point P on the circumference, the tangent line through P and the radius CP are perpendicular.
So, the answer is 90 degrees.
