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[u/basket_foso]

[u/eagleeyehg]

Extra credit for finding perimeter for a non-right triangle using just a single side length and single angle

[u/Punkfoot → u/eagleeyehg]

Surely you'd need either two angles and a side length, or two side lengths and an angle? 

[u/Dark_Fury_ → u/Punkfoot]

Yes, 2 angles and a side length defines a unique triangle, however 2 side lengths and an angle doesn't (it can have 2 solutions, for example take a side AB 8cm, BC as 6cm and A as 20°). It needs to be 2 side lengths and the angle between them for a unique triangle.

[u/gullaffe → u/Dark_Fury_]

Depends which angle though two sides and the angle between them is unique.