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The Law of Cosines

Video Summary:

SAS or SSS forms a unique triangle Triangle Side Restriction In any triangle, the sum of the lengths of any two sides must be greater than the length of the remaining side. Oblique Triangle Suggested Procedure for Solving Case 1: SAA or ASA Find the remaining angle using the angle sum formula (A + B + C = 180°). Find the remaining sides using the law of sines. Case 2: SSA This is the ambiguous case; 0, 1, or 2 triangles. Find an angle using the law of sines. Find the remaining angle using the angle sum formula. Find the remaining side using the law of sines. If two triangles exist, repeat steps 2 and 3. Case 3: SAS Find the third side using the law of cosines. Find the smaller of the two remaining angles using the law of sines. Find the remaining angle using the angle sum formula. Case 4: SSS Find the largest angle using the law of cosines. Find either remaining angle using the law of sines. Find the remaining angle using the angle sum formula.

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