Tuesday, April 7, 2015
[IB-HL_FTPR20150402] Periodicity cos a fortiori
In this article, I give a rigorous proof of the period of cosine functions, using an a fortiori argument, signaled by the use of the words “in particular”. When something is generally true for, say, all real numbers, it is “all the more” true for a particular case of a real number like zero. I use this logic to nail down the answer.
* revision for IB Mathematics HL / SL* other syllabuses that teach trigonometry