Non-Right Triangle Trigonometry
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If we want to analyze a non-right triangle (a triangle that does not have a 90 degree angle), Right Triangle Trigonometry won't work. We have to use different methods.
It is crucial to know that the angles in a triangle are labelled with capital letters (A, B, C) and the sides are labelled with lower case letters (a, b, c). Note these examples:
That simple concept is very important to being able to solve non-right triangles.
Examine each of these triangles. Note that neither the Pythagorean Theorem nor Right Angle Trigonometry can be used because neither of the triangles has a right angle.
We have two options:
One is called the Law of Sines and the other is called the Law of Cosines.
Each of them has a specific purpose and, in general, one is often easier than the other. Depending on the triangle and what information is given and what you are looking for, sometimes only one option will work. In other cases, you can use either the Law of Sines or the Law of Cosines to solve the triangle.