Solving Trigonometry Problem: 2 Variables, 2 Equations

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    Trigonometry
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Discussion Overview

The discussion revolves around solving a trigonometry problem involving two variables and two equations. Participants explore methods to find the values of x and v, discussing the relationships between the equations and the use of trigonometric identities.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents the original equations and requests help in solving for x and v.
  • Another suggests solving for v first from the second equation and using a summation formula to find x.
  • A participant expresses confusion about the summation formula and shares their attempt to solve for v, resulting in v = 0.6sinx, but notes inconsistencies in their solution.
  • One participant rephrases the original equations using x = cos(x) and y = sin(x), proposing to add the equations for further analysis.
  • Another participant questions how the equations were derived and suggests a different form for the equations involving specific trigonometric values for cos(30) and sin(30).
  • A participant points out that the assumption about the angles being in degrees is important and proposes multiplying the equations by sin(30) and cos(30) for simplification.
  • There is a correction regarding the expression for v, indicating that the earlier derived v = 0.6sinx is incorrect.
  • One participant claims to have solved the problem but does not provide details.

Areas of Agreement / Disagreement

Participants express differing methods and interpretations of the equations, with no consensus reached on the correct approach or solution. Some participants challenge each other's calculations and assumptions.

Contextual Notes

There are unresolved mathematical steps and assumptions regarding the angles used in the equations, as well as the application of trigonometric identities. The discussion reflects varying levels of familiarity with the concepts involved.

Champ07
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I've been really stumped by this one from my math class. It's a two variable trig. question with two equations. I believe there simultaneous but I'm not sure

3 = 1.2(cosx) + v(cos30)
0 = 1.2(sinx) - v(sin30)

Solve for the values of x & v

Please explain how you got your answer or show work. Thanks
 
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Well, solve for v first from, say, the 2nd eq.
Then you get a trig equation; use the summation formula to reshape it so that you can solve for relevant x's
 
Sorry I'm not familar with the summation formula. I solved for V in the second equation and got V = .6sinx.

I substituted that into the second equation and got sin = 0, 180 or 360 but then the 2nd equation doesn't check out. I know I'm doing it wrong somehow just not sure how
 
Champ07 said:
I've been really stumped by this one from my math class. It's a two variable trig. question with two equations. I believe there simultaneous but I'm not sure

3 = 1.2(cosx) + v(cos30)
0 = 1.2(sinx) - v(sin30)

Solve for the values of x & v

Please explain how you got your answer or show work. Thanks
Actually, I suspect the problem asked YOU to explain how you got your answer or shiow work. I don't have to! Let x= cos(x) and y= sin(x). then you have the two equations
3= 1.2x+ vy and 0 = 1.2x+ vy as well as the obvious equation [itex]x^2+ y^2= 1[/itex]. What happens if you add the first two equations?
 
HallsofIvy how do you get those equations?

Seems it should be
[tex] 3 = 1.2x + v\frac{\sqrt{3}}{2}[/tex]
[tex]0 = 1.2y - 0.5v[/tex]
[tex]x^2 + y^2 = 1[/tex]
 
How did I get those two equations? I copied them from the first post in this thread!
3 = 1.2(cosx) + v(cos30)
0 = 1.2(sinx) - v(sin30)
I now see, looking more closely, that it might be good idea to multiply the first equation by sin(30) and the second equation by cos(30). Although it wasn't said, I assume that is "30 degrees" so that cos(30)= [itex]\sqrt{2}/3[/itex] and sin(30)= 1/2.
 
Champ07 said:
Sorry I'm not familar with the summation formula. I solved for V in the second equation and got V = .6sinx.

That's the right idea, but the solution to 0 = 1.2(sinx) - v(sin30) = 1.2(sinx) -v(0.5) isn't v = 0.6 sin x.
 
i just solved it, long prob
 

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