hello all you hopefully mathy people, this is a cry for help. we started the trig half of our class this semester and i'm practically swimming against a tidal wave. i've never been so good at this kind of thing (might help if the teacher didn't sound like a robot right after lunch...zzz), can anyone give me some kind of helpful studying tips for math? i really don't quite get it. thank you.

Alright, I'll see what I can do. I hate trig :lol:

Are you familiar with functions? If so, good. If not, get familiar.

A trig function is merely something that relates geometric values, such as sides of a triangle. In trig class, chances are you'll only use trig to study relationships in triangles, specifically right triangles.
The three major trig functions are sine, cosine, and tangent (abbreviated sin, cos, and tan). The simplest thing you need to know about these are that they relate sides of a right triangle.

All this only works for right triangles:
Think of a right triangle in your head (or find a picture or whatever) and lable the legs 'a' and 'b' and the hypotenuse 'c'. Then label the angles opposite of each side A, B, and C respectively.

The sine of an angle is the ratio of the opposite side to the hypotenuse. So sin(A) = a/c, sin(B ) = b/c.
The cosine of an angle is the ratio of the adjacent side to the hypotenuse. So cos(A) = b/c, cos(B ) = a/c.
The tangent of an angle is the ratio of the opposite side to the adjacent side. So tan(A) = a/b, tan(B ) = b/a.

That is just about all you do in an entire quarter of Trig :rofl:
The quick way to remember all this is a weird word/acronym/thingy called "SohCahToa". Anyone who has had high school trig know this thingy, and it does help to remember them at first.
This is how:
Soh = Sine: Opposite/Hypotenuse
Cah = Cosine: Adjacent/Hypotenuse
Toa = Tangent: Opposite/Adjacent



Wow, that was long. Hope that helps :)

In academic bowl, we seem to have a good number of questions dealing with quickly calculating trig functions, so it's good to know some of the more "common" ones right off... A good way to do this is to grab your handy graphic calculator, put it in Decimal mode (rather than Radian), then enter the graphing function. Enter "sin x", or "cos x", or "tan x". If you don't get a "wavy" line, go into the Zoom function, and use "ZTRIG" for the option to view it. Now use the Trace function to get the values. For example, type in 30 on the sin wave. When X=30, Y=0.5. On cos, type in 60. Y comes back as 0.5.
This makes sense when you think of it as a triangle with angles 30, 60, and 90. In geometry you probably learned the ratio of sides on this type of triangle is 1 for the short leg, 2 for the hypotenuse, and radical 3. Using "Soh-Cah-Toa", the sine of 30 degrees, the leg opposite the 30 degree angle (which is 1), over the hypotenuse (2) is 0.5. The cosine of 30 is radical three (the leg adjacent to the 30 degree angle) over 2, the hypotenuse. That's radical 3 over 2, which comes out to .866 when you do it on a calculator.
If you play with the graphs of the trig functions (using trace to get a Y from whatever X's you put in), it gets easier to deal with.

thanks guys, you beat my teacher to the sohcahtoa thingy. it helped me a bunch, we had a test today I think (hope) I did well. thanks for the help!

Glad we could help :)

Trig's tricky. I just happen to be the type that saw the light first try. Trig is based on the idea of triangles (obviously), and the most common used is the right triangle. The two legs adjacent to the 90 degree angle are given the name 'a' and 'b' with the hypoteneuse 'c.'

In the coordinate plane, the quardrant that has:

x and y both positive is quardant 1 (top right)

x negative; y positive is quadrant 2 (top left)

x and y both negative is quardrant 3 (bottom left)

x positive; y negative is quadrant 4 (bottom right)

In Quardrant 1 A ll these values are positive,
in Quadrant 4 C os and its inverse are positive,
in Quadrant 3 T an and its inverse are positive, and
in Quardrant 2 S in and its inverse are positive.

So starting at the top and going clock wise A, C, T, S are positive. A good acronym for "ACT SUCKS."



If i triangle is based on the origin (having the hypoteneuse and a side touching it) the following values are given:

sin=y/r
cox=x/r
tan=y/x
cot=x/y
sec=r/x
csc=r/y

R= the length of the hypoteneuse (ALWAYS positive)
X=the x value of the triangle
Y=the y value of the triangle

For example: A triangle is based on the origin (0,0) with point (5, 12), give the functions.

x=5
y=12
and r=13 (the hypoteneuse)

so sin=y/r=12/13
cos=x/r=5/13
tan=y/x=12/5
cot=x/y=5/12
sec=r/x=13/5
csc=r/y=13/12

Another example, if a triangle is based on the origin and has the point (-3,-4)
x=-3
y=-4
r=5

so sin=y/r=-4/5
cos=x/r=-3/5
tan=y/x=4/3
cot=x/y=3/4
sec=r/x=-5/3
csc=r/y=-5/4

and since the triangle is in quadrant 3 because the point given is (negative, negative), using ACTS, tangent and its inverse are the only functions positive.

If you ever need any help, email me.

Joseph Gracy

Good explanation
I think it's easier though, to go from quadrant 1-4 so you get ASTC which means "All substitute teachers cuss" :rofl:
My math teacher gave us that one :)

I guess our teacher was wanting us to be good students. He told us "All Students Take Calculus"... :P