SOLUTION: Provided AB has length 5 cm, BC has length 3 cm, and the measurement of angle A is 30 degrees, draw triangle ABC, and describe why these conditions do not determine a unique triang

Algebra ->  Angles -> SOLUTION: Provided AB has length 5 cm, BC has length 3 cm, and the measurement of angle A is 30 degrees, draw triangle ABC, and describe why these conditions do not determine a unique triang      Log On


   



Question 891836: Provided AB has length 5 cm, BC has length 3 cm, and the measurement of angle A is 30 degrees, draw triangle ABC, and describe why these conditions do not determine a unique triangle. I'll try to draw the shape, but I don't know how to describe why the conditions don't determine a unique triangle. I've been stuck on these problems for a week now. They're actually due next week, but I don't want to try it at the last minute.
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Provided AB has length 5 cm, BC has length 3 cm, and the measurement of angle A is 30 degrees, draw triangle ABC, and describe why these conditions do not determine a unique triangle. I'll try to draw the shape, but I don't know how to describe why the conditions don't determine a unique triangle. I've been stuck on these problems for a week now. They're actually due next week, but I don't want to try it at the last minute.

Since we’re given 2 sides and a NON-INCLUSIVE angle, we need to use the Law of Sines to determine
how many distinct triangles can be formed. If more than one (1) triangle can be formed from the
given measurements, then the triangle is NOT UNIQUE, or NOT DISTINCT.
Since side BC is opposite angle A, then side BC = a = 3
Also, since side AB is opposite angle C, then side AB = c = 5
Using the law of sines, we get: sin+A%2Fa+=+sin+C%2Fc
%28sin+30%5Eo%29%2F3+=+sin+C%2F5 ------ Substituting angle A, and sides a & c to determine angle C
3sin+C+=+5sin+30%5Eo ------ Cross-multiplying
sin+C+=+%285+sin+30%5Eo%29%2F3
sin C = .833333
Angle C = sin%5E-1%28.83333%29 = 56.44%5Eo56%5Eo
This means that the 3rd angle, or angle B = 180%5Eo+-+%2830%5Eo+%2B+56%5Eo%29, or 180%5Eo+-+86%5Eo, or 94%5Eo

Now, the reference angle of angle C is in the 2nd quadrant, and is: 180%5Eo+-+56%5Eo, or 124%5Eo.
Now, with angle A being 30%5Eo, and the reference angle of angle C being 124%5Eo, a 2nd triangle,
with an angle measurement of B = 180%5Eo+-+%2830%5Eo+%2B+124%5Eo%29, or B = 26%5Eo CAN BE FORMED.

Therefore, the given triangle with the given measurements represents a NON-DISTINCT or
NON-UNIQUE triangle, since 2 triangles: one measuring:
30%5Eo, 56%5Eo, and 94%5Eo, and another measuring:
30%5Eo, 124%5Eo, and 26%5Eo, can be formed.