Explaination of theory.
asked Jul 23, 2015 in Trigonometry Answers by callie

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:

To avoid this verification in future, please log in or register.

1 Answer

Best answer

Theta/2 is between (pi)/4 and (pi)/2 (45 and 90 degrees). This puts all trig functions in the first quadrant where they are all positive. Cosine is negative in quadrants 2 and 3 only. (Quadrant rule for quadrants 1 to 4 is All Silver Tea Cups, or All, Sine, Tangent, Cosine positive rule.) So cos(theta/2)<0 is false when (pi)/2<theta<(pi).

answered Jul 23, 2015 by Rod Top Rated User (509,800 points)
Welcome to MathHomeworkAnswers.org, where students, teachers and math enthusiasts can ask and answer any math question. Get help and answers to any math problem including algebra, trigonometry, geometry, calculus, trigonometry, fractions, solving expression, simplifying expressions and more. Get answers to math questions. Help is always 100% free!
80,487 questions
84,403 answers
2,090 comments
67,764 users