Please answer this quickly.

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

Does the point (1, sqrt 7) lie on circle shown.

Angle xyz is formed by segments xy and yz on the coordinate grid below: a coordinate plane is shown. angle xyz has endpoints at 3 comma negative 1 and 6 negative 2 and 3 comma negative 3 and measures 36.87 degrees. angle xyz is rotated 270 degrees counterclockwise about the origin to form angle x′y′z′. which statement shows the measure of angle x′y′z′?