In week 16 of precalc 11 we went over more trig. We learned how SOH CAH TOA works on a chart. SOH CAH TOA can be translated to SYR CXR TYX (R being the rotation angle). This is how you find triangles on a graph. Most problems we work with involve finding R with Pythagoras theorem, then using SYR CXR TYX to find an angle inside the triangle. We also learned about an important rule called CAST. basically it goes counter clockwise from Q4, being C, Q1 being A, Q2 being S and Q3 being T. The acronym is for Cosine, All, Sine and Tangent. In their respective quadrants, they are positive and they are negative in all other ones.

The problems we will work with is seeing if something is positive or negative. for example we will have something like “is sin 305 positive or negative?” then we will find that 305 is in Q4 or (or the C quadrant) and since it’s sine, it is negative. It’s negative because since sin = y/r, the Y in Q4 is negative, making the fraction negative, making sin a negative number.

Another thing we learned about is special triangles. Basically, 30, 45 and 60 degrees (and rotation angles with those as reference angles) are important to remember because you don’t even need a calculator to work with them. We can memorize the exact values of a triangle with these degrees. Basically we memorized these two triangles and their values.