Name: Bryant
Who is asking: Other
Question: c 2 = a 2 + b 2 - 2ab cos C cos(180 degrees - C) = -cos C Hi,
In the diagram below of a triangle with angle C obtuse, I extended the line segment BC drew a perpendicular from A to meet this extended line at D. Let x be the length of CD and h the length of AD. Triangle ABD is a right triangle and hence = (a + x) 2 + h 2 = a 2 + 2ax + x 2 + h 2 = a 2 + b 2 +2ax Can you complete the proof? Penny
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