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ASS Theorem


ASSTheorem

Specifying two adjacent side lengths a and c of a triangle (with a<c) and one acute angle A opposite a does not, in general, uniquely determine a triangle.

If sinA<a/c, there are two possible triangles satisfying the given conditions (left figure). If sinA=a/c, there is one possible triangle (middle figure). If sinA>a/c, there are no possible triangles (right figure).

Remember: Don't try to prove congruence with the ASS theorem or you will make an ASS out of yourself.

An ASS triangle with sides a and c and excluded angle A with sinA<a/c has two possible side lengths b,

 b=ccosA+/-sqrt(a^2-c^2sin^2A).

The SSS or SAS theorems can then be used with either choice of b to determine the angles B and C and triangle area K.


See also

AAA Theorem, AAS Theorem, SAS Theorem, SSS Theorem, Triangle

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Cite this as:

Weisstein, Eric W. "ASS Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ASSTheorem.html

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