Geometry help me please

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

Given: hf || jk; hg ? jg prove: fhg ? kjg to prove that the triangles are congruent by asa, which statement and reason could be used as part of the proof? fgh ? kgj because vertical angles are congruent. jkg ? hfg because vertical angles are congruent. fhg ? jkg because right angles are congruent. hfg ? kjg because alternate interior angles are congruent.

How many solutions does the nonlinear system of equations graphed bellow have?