Precalculus
Precalculus
Make sure to focus on logarithm, polynomial, and exponential functions. In addition, work on synthetic division and analytical geometry. Lastly, learn about sigma notation, sequences/sums, and proof by induction.
Stuff to remember:
Trig:
pi = 180 degrees
Soh Cah Toa
Sin = Opposite/Hypotenuse
Cos = Adjacent/Hypotenuse
Tan = Opposite/Adjacent (= sin/cos)
Reciprocals
Csc = Hypotenuse/Opposite or 1/Sin
Sec = Hypotenuse/Adjacent or 1/Cos
Cot = Adjacent/Opposite (= cos/sin) or 1/Tan
Inverse Trigonometric Functions
Note that using the power of -1 here is not actually raising it to the -1 power, but rather a notation often used for inverse functions that may appear on your calculator.
tan^-1 aka (arctan) is the inverse function for tangent
cos^-1 aka (arccos) is the inverse function for cosine
sin^-1 aka (arcsin) is the inverse function for sine
Application: As sin(pi/2) = 1, arcsin(1) = pi/2
These come in handy for calculus
Functions
One to One = Injective
Onto = Surjective
Both = Bijective
Vertical line test:
For a graph to represent a function, it would need to have 1 inout for each output, IE any vertical line would need to hit the graph at most once. Using this test, we know the equation of a circle isn’t considered to be a function.
Horizontal line test:
Use the horizontal line test to see if it is surjective, injective, bijective, or none. For a function to be one to one, the graph of the function crosses any horizontal line on the graph at least once. Whereas, for onto it would need to cross at most once. For it to be both onto and one to one, the graph would need to cross any horizontal line at most one time.
Resources
Domain, Range, and Signs of Trigonometric Functions