Question 1 • Fall 24 GMS Geometry: Concepts and Connections B
The law of cosines is c² = a² + b² − 2ab cos(C), where C is the included angle. Here the sides around the 100° angle are 9 and 10, and the opposite side is s, so s² = 9² + 10² − 2(9)(10)cos(100°). That matches choice D.
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