WEBVTT

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Here is the problem: Solve the triangle with sides a equals 4, b equals 7, c equals 9.

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Side a is opposite angle A, b opposite B and c opposite C. This is the SSS case.

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Each angle from the law of cosines.

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Area and perimeter.

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So the answer is a equals 4, b equals 7, c equals 9; A equals 25.2087653°, B equals 48.1896851°, C equals 106.6015496°; area equals 13.41640786, perimeter equals 20.

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Three measurements including a side normally fix a triangle. Two sides with a non-included angle (SSA) can give zero, one or two triangles.

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Triangle 1: angles sum to 180°; a/sin A equals 9.391485505 equals c/sin C equals 9.391485505.