Trig Identities Trigonometric Functions

Canceling and Trig Identities

photo (37)

How do you teach this topic so that students don’t make this mistake? (Or do you just rail on their earlier teachers?)

Thanks to Kristen Fouss for the submission.

2 replies on “Canceling and Trig Identities”

I don’t allow the word “cancel” to be used in these situations. They have to say a whole big sentence like “Dividing both sides of the equation by …” or “dividing top and bottom of the fraction by …” or “because these are inverse functions…”

I also tell lots of jokes like 16/64 = 1/4 (by canceling the 6) and sin x / n = 6 (by canceling the n) and so on. It’s always illuminating to see whose number sense treats the “canceling the 6” operation as potentially plausible.

Comments are closed.