Segments BA and CA are drawn perpendicular to two chords. The segments are congruent, so that makes the two chords congruent (they are the same distance from the center of the circle). So segments GF and HE are congruent.
In the second problem, it helps to ignore the pieces of information you don't need. Angle GET is formed by two secants, IE and NE. I've attached a diagram that shows the angle you're trying to find and its TWO intercepted arcs. A fact about circles is that if the angle is formed by two secants (their intersection is outside the circle), the measure of the angle is half the DIFFERENCE of the measures of the intercepted arcs.
The measure of angle GET = 1/2 (74 - 18) = 1/2(56) = 28 degrees.