posted by jennifer on .
I have heard that trig CAN be super easy, that there are just, like, 10 rules you need to memorize then all the problems are easy.
... Does anyone know what these are?
I would say they are the definitions of tan, cot, sec and csc in terms of sin and cos,
tan = sin/cos
cot = cos/sin
csc = 1/sin
sec = 1/cos
sin^2 + cos^2 = 1
the law of sines
the law of cosines
sin (a + b) = sin a cos b + cos b sin a
cos (a + b) = cos a cos b - sina sin b
tan (a + b) =
(tan a + tan b)/[1 -(tan a tan b)]
Others may differ