# 9.5 Oblique Triangles, the Law of Sines

**Oblique Triangles • Law of Sines • Case 1: Two Angles and One Side • Case 2: Two Sides and the Angle Opposite One of Them • Ambiguous Case**

To this point, we have limited our study of triangle solution to right triangles. However, *many triangles that require solution do not contain a right angle. Such triangles are called* **oblique triangles.** We now discuss solutions of oblique triangles.

In Section 4.4, we stated that we need to know three parts, at least one of them a side, to solve a triangle. There are four possible such combinations of parts, and these combinations are as follows:

Case 1.

*Two angles and one side*Case 2.

*Two sides and the angle opposite one of them*Case 3.

*Two sides and the included ...*

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