Explanation: Angle C and the 80 degree angle are vertical angles. Vertical angles are always congruent. Angle F is equal to angle C because they are alternate interior angles.
============================================
Problem 12
Answer: 100 degrees
Explanation: Solve the equation E+F = 180, where F = 80 found earlier above. You should get E = 100.
============================================
Problem 13
Answer: 80 degrees
Explanation: This was mentioned earlier in problem 11.
============================================
Problem 14
Answers: complement = 50, supplement = 140
Explanation: Complementary angles always add to 90. Supplementary angles always add to 180. An example of supplementary angles are angles E and F forming a straight line angle.
A rational number is a number that can be written into a fraction. pi, some square roots, e, etc., are irrational numbers(numbers that cannot be written into a fraction).
