.
A) One central angle of a circle is triple the measure of another central angle. What other information does this enable you to know?
The corresponding arc is triple the measure of another corresponding arc.
B) Prove why an inscribed angle subtended by a diameter is a right angle.
Because the measure of an inscribed angle is half the measure of the subtended arc.
See the lesson
- An inscribed angle in a circle
in this site.
By the way, you have this free of charge online textbook on Geometry
GEOMETRY - YOUR ONLINE TEXTBOOK
in this site.