Question

My teacher gave us this cheat sheet for review for our upcoming exam:

http://screencast.com/t/jDvuiN83fmpg

My issue is that I do not understand how to view these questions. I.E. cos(theta)=0, then theta=?

I don't know how to even solve that. Or derive any of the facts from that sheet.

Answer 1

@RaphaelE: I've looked at the one document you've listed and see that it contains just values of the trig functions, nothing more; there are no actual problems there. Have you a list of practice problems as well? If so, please pick one or two such problems and post them, one at a time. You'd probably get more responses were you reasonable about the number of questions you post, and also more responses if you show what you've already done towards solving those questions/problems.

Answer 2

They're not specific problems. I would just like to know where to derive all of that information on that sheet, if that makes sense.

Answer 3

Once again: the illustration you have posted is a reference table; it does not contain trig problems (other than that you do have to learn at least some of the trig functions and be able to find their values from the table).

Answer 4

Raphael, are you familiar with the unit circle?
That's what we would use to derive all of these special values.

Answer 5

Yeah I know the unit circle. From where in the unit circle do we get that information?

Answer 6

Lemme show you one example really quickly :)

Answer 7

If we draw a line straight down, we get a triangle.

Answer 8

The hypotenuse is of length 1 (it's the radius of the circle).

Answer 9

Whichever approach you use, you do need to learn the three basic trig functions: the sine, cosine and tangent. Once you understand and remember how those are defined, finding the actual values of the sine, cosine and tangent becomes a lot easier. zepdrix' method is straightforward and clear.

Answer 10

Have you learned some method for remembering the trig relations for a triangle?
`Soh Cah Toa`
Does that sound familiar?

Answer 11

Yeah, I know the relations. Opp/hyp, adj/hyp, opp/adj

Answer 12

Lemme label the missing sides of this triangle a sec.

Answer 13

Then as soon as y ou are able to identify the values of the opp side, adj side and the hypotenuse, you'll be in a position to find the values of the sine, cosine and tangent from a diagram like that zepdrix is drawing, or from the table you have posted.

Answer 14

http://upload.wikimedia.org/wikipedia/commons/7/7b/Trig_functions_on_unit_circle.PNG