Can you use trigonometric functions for any kind of triangle?

1 Answer
Jim H
Mar 26, 2015

It depends on what you mean by "use trigonometric functions".

The Law of Sines tells us that for any triangle: labelled with
a = length of the side opposite angle A
b = length of the side opposite angle B
c = length of the side opposite angle C
we have:

sinA/a=sinB/b=sinC/c

(So also, by algebra: a/sinA = b/sinB = c/sinC)

The Law of Cosines generalizes the Pythagorean Theorem.
It says that in any triangle labelled as above, we have:
c^2=a^2+b^2-2ab cosC
b^2=a^2+c^2-2ac cosB
a^2=b^2+c^2-2bc cosA

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