An oblique triangle is a triangle that contains no right angles. Oblique
triangles are not as easy to solve as right triangles because three parts of the
triangle must be known in order to solve the triangle. Also, with oblique
triangles, we can no longer use two of the simplest techniques for solving right
triangles--the Pythagorean Theorem and the fact that two acute angles are
complementary. Instead, two new techniques are needed: the Law of Sines and
the Law of Cosines. These laws are formulas that relate the parts of
triangles to each other. They work for all triangles, including right
triangles, but since right triangles have special properties we use simpler
methods to solve them.
In the following lessons, we'll review oblique triangles and learn the Law of
Sines and the Law of Cosines. In addition to that, we'll also see a new way to
find the area of a triangle.
