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how the eff do i teach myself trig in an hour

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costargh:
What are the 2 triangle thingos that you use to get your reference angles?
And when do you use them? haha

reg:
You just need to get used to it.

We get to the stage:
tan(2x) = -sqrt(3).

tan(x) equals sqrt(3) at pi/3, and tan is negative in the 2nd and 4th quadrants  (ASTC).

Hence, we need pi-pi/3, 2pi-pi/3.

and we need solutions from 0 to 2pi .. (which is really 4pi because we have  tan(2x), so we change the domain)

pi - pi/3, 2pi - pi/3, 3pi - pi/3, 4pi - pi/3

so eventually we have:

2x = 2pi/3, 5pi/3, 8pi/3, 11pi/3
x = 2pi/6, 5pi/6, 8pi/6, 11pi/6

You just do pi-pi/3, 2pi-pi/3 until you consume all the required periods.

As far as exact values go, I just memorized the sin row, the cos row is sort of an inverse (easy to remember once you have sin down), and then tan is just division. I'll write out the table in the exam. But you should prolly go for the triangles :P

Galelleo:
lol ... its hard to explain/draw the triangles on this... but here , i did it in paint  lol


[img]http://img207.imageshack.us/img207/5792/loldm4.th.jpg[/img]

Fitness:

--- Quote from: "costargh" ---What are the 2 triangle thingos that you use to get your reference angles?
And when do you use them? haha
--- End quote ---

Ok well I too did a version of these triangles. See if you can follow this one easier ...

Galelleo:
Basically, the triangels are from the smallest possible integers for the sides when you have the angels of 45, 60, and 30 on a right angld triangle.

lol if that makes sense...
the smallest sided equilateral triangle has sides of 1 but we use 2 beacuse we half it to find the angles easier... uh i just confused myself
basically when you cut them in half you get that picture, and theyre the values of sin (O/H), cos (A/H), and tan (O/A).

Alternatively, you can think about it for a moment and picture the general graph, you know cos starts at 1, when x=0... and you know the period is 2pi, so you just picture where on the graph, pi, pi on 2, pi on 4, pi on 3, pi on 6, would be and you can memories/guess the values of cos /sin/tan at that point... although its probably easier to have a calculater ;)

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