Tuesday, October 25, 2011

4.2 Trigonometric Functions: The Unit Circle




Definitions of Trigonometric Functions


Let t be a real number and let (x,y) be the point on the unit circle corresponding to t.

sin t = y csc t = 1/y y cannot =0

cos t = x sec t = 1/x x cannot =0

tan t = y/x cot t = x/y y cannot =0



In Other Words
SOHCAHTOA CHOSHACAO

sin = opp/hyp csc = hyp/opp

cos = adj/hyp sec = hyp/adj

tan =opp/adj cot = adj/hyp



Even and Odd Trigonometric Functions

The cosine and secant functions are even

cos(-t) = cos(t) sec(-t) = sec t

The sine, cosecant, tangent, and cotangent functions are odd.

sin(-t) = -sin(t) csc(-t) = sec(t)

tan(-t) = -tan(t) cot(-t) = -cot(t)







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