Help i tried to do it but not sure..

Acircle has a diameter will endpoints of (-2,8) and (6, 4). what is the center of the circle

Find the distance between the point (-3,-4), and (see the picture below)

Given that δabc is similar to δdef, which is a possible trigonometric ratio for ∠d? a) tan d = 24 30 b) tan d = 30 24 c) tan d = 18 24 d) tan d = 24 18