Troubleshooting Simultaneous Equations with Trigonometric Functions on TI-89

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SUMMARY

The discussion centers on troubleshooting the SOLVE() function on the TI-89 calculator when solving simultaneous equations involving trigonometric functions. The user initially encountered incorrect results while solving four equations derived from two Free Body Diagrams. The equations included forces in both X and Y directions, with variables CD, CB, BA, and Theta. After re-evaluating the input, the user successfully obtained the correct answers: BA=80.7 lb, CD=65.9 lb, CB=57.1 lb, and Theta=2.95 degrees.

PREREQUISITES
  • Understanding of trigonometric functions and their application in physics.
  • Familiarity with the TI-89 calculator and its SOLVE() function.
  • Knowledge of Free Body Diagrams and force analysis.
  • Basic algebra skills for manipulating simultaneous equations.
NEXT STEPS
  • Explore advanced features of the TI-89 calculator for solving complex equations.
  • Learn about troubleshooting common issues with the TI-89's SOLVE() function.
  • Study the principles of static equilibrium in physics to enhance understanding of Free Body Diagrams.
  • Investigate alternative software tools for solving simultaneous equations, such as MATLAB or Wolfram Alpha.
USEFUL FOR

Students in physics or engineering courses, educators teaching mechanics, and anyone using the TI-89 calculator for solving trigonometric equations in practical applications.

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Homework Statement


My problem is getting the SOLVE() function to work correctly. I have used it plenty of times in the past, but when I put in these 4 equations to solve simultaneously, it gives me the wrong answers. My Professor said that TI-89's sometimes have problems when having to solve trig functions, like solving for theta, gamma, phi, etc., inside of simultaneous equations.

The problem had me break it up into 2 Free Body Diagrams.

here are the exact 4 equations that I have:

1st free body Diagram:
Sum of Forces in the X direction:
CB*cos(theta)-CD*cos(30)=0
Sum of Forces in the Y direction:
-CB*sin(theta)+CD*sin(30)-30=0

2nd free body diagram:
Sum of forces in X direction:
-CB*cos(theta)+BA*cos(45)=0
Sum of forces in Y direction:
CB*sin(theta)+BA*sin(45)-60=0

The Variables I have to solve are:CD,CB,BA,Theta.
The correct answers are:
BA=80.7 lb
CD=65.9 lb
CB=57.1 lb
Theta=2.95 degrees.

The Professor verified that my equations were right. Please if anyone could help me with this, it would seriously be a breakthrough for me. Thanks!
 
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OK, i must have punched something in wrong, because it worked out perfectly this last time I tried it.
 

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