Unit circle

[Jess]

I should have had the unit circle memorized by now, but I STILL struggle. I can't come up with the answer(s) in 5 seconds or one minute.

this is trig, by the one. you know, sin of 30 degrees is 1/2. I also have memorized the radians of the angles (in degrees) but I can't say what 3pi/2 is in 5 seconds

I need help with this. we're being quizzed on the unit circle everyday, and I want to do well.

[Peace God]

http://blog.ssis.edu.vn/chrischoi/files/2010/04/UnitCircle.gif

^You should look for the patterns in the unit circle.
Ex: The sines, cosines, tangents on the graph are the same on the opposite side, except for the signs (+positive or -negative).

http://compuhighwv.com/classes/trigonometry/lesson02_files/circlequadrants.jpg

^The 4 quadrants of a unit circle are just like your normal x,y coordinate planes...meaning the signs(+positive or -negative) for each (x ,y) value on a normal (http://www.gamedev.net/reference/articles/snippets1/cartesian.jpg) quadrant are the same as the signs for the (cos,sin) values on the unit circle.


In the first quadrant the x and y values, or in this case, sine and cosine values are both positive. The second quadrant has a negative cos and a positive sin. In the third one the cos and sin values are both negative. And in the last quadrant the cos value is positive and the sin value is negative.


http://img716.imageshack.us/img716/779/sine20pic20good.jpg

This is how a normal 2π(360°) period breaks down.

[Jess]

I have the same sheet with all those values but for some reason I STILL can't memorize it. my mind goes blank. I always have to look back

[Peace God]

I always have to look back
There's nothing wrong with that, keep glancing over it. There's no doubt that you'll memorize it eventually...and then, like me, forget it all during summer break. :P

[Malcolm Tucker]

I know it off. Mainly because if you look at the Cos X and Sin X values, there is a pattern. The top right is all positive, bottom right all negative, top left cos negative, and bottom right sin negative. The middle one is always 1 over root 2, and so on. Just try and memorize the pattern :)

[Xerxes]

I'm actually covering those topics right now in my precalculus class... And my memorization strategy is just to write each of the equations down 10-15 times each.