Five PreCalc Groaners
Question: How do trig functions greet each other?
Answer: With a sine wave.
Question: What kind of angle never quits?
Answer: A triangle.
Question: What do you call articles of Arctic clothing that can be worn together?
Answer: Polar coordinates.
Question: What did the psychology student asking the question "Who am I?" have in common with the student trying to solve the matrix equation AX = A, where A and X are 2x2 matrices?
Answer: Both were searching for an identity.
Question: What do you call a prehistoric prison?
Source: June Oliver. Algebra, Trig, and Pre-Calc Laughs. 2000