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Friday, March 16, 2012

Trigonometric Points

Some of you may be having a hard time remembering the trigonometric points for radians. Well, I know I am.
Let's have a look here:
Notice that they all have 2's as denominators, which cuts down the difficulty of remembering these by half (get it?), with the exception of π/4, whose denominators are √2―no big deal.

All I do to remember these is say to myself: "1, 3, 1" twice. Whether you start at 0π (or 2π) or π/2, this pattern will work.

Now, the other three quarters of the circle are easy to coordinate if you know these three (I exclude the 0, 90, 180, 270 and 360 degrees because they are obvious). Just remember that the quadrants (from 1st to 4th, (cos, sin)) go like this: (+,+), (-, +), (-,-) and (+, -).
There you go, a perfectly and exactly coordinated circle!


  1. I honestly have to say, I never even noticed that all the coordinates have some form of two-ness in their denominators. I always remembered the whole fraction. More things to tell my own future students to help them remember stuff! Do you know that you are making me a better teacher? :)

    1. Well, I have great pleasure creating these posts and I am flattered to know that it is not only helping my classmates, but also the teacher! :)