What can be proven true in the diagram is the statement in letter C. angle CGB is complementary to angle AGD. It is because they both had the same vertex which is point G. Complementary angles are angles which are equal to 90 degrees wherein when you add both angles which are obviously 45 degrees, the sum is 90 degrees.
You use (y2-y1)/(x2-x1) so if you have two points (ex: (1,2) and (2,4)), plug in those number into the formula
(4-2)/(2-1) = 2/1 = 2 so the slope (or instantaneous rate of change) is 2 for those two points<span />
