SIN, COS, TAN help?

  1. Hello,

    I'm having some problems. So for geometry class today, the teacher taught us this COS, SIN, TAN stuff. I got the concept how to get the fractions from the triangle and everything. Problem is how to plug it in the calculator. I have a basic TI-30XA, and I'm trying to plug in fractions for the SIN, COS, and TAN, but I have no clue how to plug it in easily. For example the fraction : 16 over 34. How do I get the SIN of it?

    Its really urgent someone replies back. I have been trying all night, and I have a chemistry test tomorrow, so I can't spend all my time working on geometry just to plug in something in the calculator.

    Thanks,

    ArcherofScience
     
  2. jcsd
  3. micromass

    micromass 18,964
    Staff Emeritus
    Science Advisor
    Education Advisor

    Just calculate 16/34 with you calculator and then hit the SIN button.
     

  4. I tried it, it worked!! Thankyou thankyou thankyou soooo much. Your like the coolest person yet! I feel like a complete idiot not even realizing that it was this simple. Thankyou you saved my life tonight with Homework. Woohoo! :D.

    thanks Micromass.
     
  5. micromass

    micromass 18,964
    Staff Emeritus
    Science Advisor
    Education Advisor

    Do be careful. Your calculator probably calculates the sine of an angle in degrees. You can check by putting in sin(90). If it outputs 1, then your calculator is set to degrees. This is ok if your geometry homework deals with degrees. But sometimes you need another thing called "radians". If you want to calculate the sine of something in radians then you should adjust your calculator.

    If you don't know what a radian is, then just ignore this post.
     

  6. I looked at my calculator and it says degree on top, so I guess i'm fine. :), thanks again btw.
     
  7. HallsofIvy

    HallsofIvy 40,558
    Staff Emeritus
    Science Advisor

    Are you sure you want to? In working with triangles, you take the sine of an angle and I don't see how that would be got as a fraction. If you have a right triangle with one leg of length 16 and hypotenuse of length 34, then the fraction 16/34 is the sine of the angle opposite that leg. If you were to use the "inverse function" button and "sine", that will give you the inverse sine- giving the angle that has sine equal to 16/34, NOT the sine of 16/34.


     
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