Cosine Rule Problems - Solve Arbitrarily Chosen Triangles

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    Cosine Cosine rule
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SUMMARY

The discussion centers on the application of the Law of Cosines for solving triangles with arbitrary side lengths and an included angle. Participants confirm that selecting any two sides (a, b) and the angle (θ) between them will yield the third side (c), provided that the angle is less than 180 degrees. The conversation emphasizes that if the angle exceeds this limit, the triangle can still be formed by adjusting the sign of the calculated value for c, indicating the flexibility of the Law of Cosines in triangle construction.

PREREQUISITES
  • Understanding of the Law of Cosines
  • Basic knowledge of triangle properties
  • Familiarity with trigonometric functions
  • Ability to perform algebraic manipulations
NEXT STEPS
  • Study the derivation of the Law of Cosines
  • Practice solving triangles using the Law of Cosines with varying angles
  • Explore applications of the Law of Cosines in real-world problems
  • Learn about the Law of Sines for comparative analysis
USEFUL FOR

Students studying geometry, mathematics educators, and anyone interested in solving triangle-related problems using trigonometric laws.

nDever
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Hey,

If I wanted to make up problems that are solved using the law of cosines, shouldn't it work out even if I arbitrarily choose side a, b, and θ? After all, any two sides and an angle between them form a triangle. Correct?
 
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Yes correct. I'm curious to know why you think choosing sides a b and theta wouldn't give you an answer for c.
 
You're OK as long as the angle is < 180 deg.
 
mathman said:
You're OK as long as the angle is < 180 deg.

Even then you'd just have a triangle in the other direction. You would just have to change a sign(no pun intended).
 

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