Trigonometry Page

radians and degrees: for reasons not totally relavant for simple trigonometry, there exists a unit of angular measure called radians. This has something to do with arc length, and as a bonus, it makes calculus a bit easier. For a unit circle (a circle with radius 1), one radian sweeps out an arc of length 1.
Conversion: Pi radians = 180 degrees; Pi/2 radians = 90 degrees

sin(t)
tan(t) =

k is a constant Identities: k*sin^2(t) + k*cos^2(t)= k cos(-t) = cost(t)

Law of Sines:
sin(A)/a + sin(B)/b + sin(C)/c
where you have a triangle with sides a,b,c, and the angle opposite a is A, and so on for B & C.

Law of Cosines:
a^2 = b^2 + c^2 - 2bc*cos(A)
b^2 = a^2 + c^2 - 2ac*cos(B)
c^2 = a^2 + b^2 - 2ab*cos(C)

exponential equivalents:
sin (t) = (e^it - e^-it)/2i
cos (t) = (e^it + e^-it)/2

Contact me at jdemaa17@calvin.edu

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This page was last updated created September 17, 1996.