Trig functions
From Math Wiki
Contents |
Definitions
Sin- the abbreviation for the trig function Sine.
Tan- the abbreviation for the trig function Tangent.
Cos-the abbreviation for the trig function Cosine.
Theta ( θ )- the sign used to represent an angle.
Soh Cah Toa
Sin = Opposite over Hypotenuse
Cos = Adjacent over Hypotenuse
Tan = opposite over Adjacent
Determining Which Side is Which
To solve for theta you will first need to decide which trig function you are going to use. (SohCahToa as explained above) But how do you know which side is opposite, which side is the adjacent, and which side is the hypotenuse? Follow this example:
In the link provided above, just pretend that: 
(All the sides are labeled for you already)
Although if solving for B then the sides would be labeled differently!
The hypotenuse is always the side across from the 90˚ angle.
The opposite is always across from the angle you're solving for.
The adjacent side is the side that is next to the angle you're solving for. (The side that's not the hypotenuse)
Special Triangles
The Law of Sines
The Law of sines is used to find a side or angle measurement when the triangle isn't 180 degress.
The formula is SinA/a=SinB/b=SinC/c
The Law of Cosines
The law of cosines can be used with any triangle. It is only useful however if you are given at least 2 side lengths, and a minimum of 3 pieces of information. It can be used to solve for a side, or an angle.
Formula is a^2=b^2+c^2-2ab*cosA
