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anonymous

  • 5 years ago

is my work correct ? here is the problem: tan(arccos(-1/2)+arccos(2/3)) let A=arccos(-1/2) let A=arccos(2/3) tan(A+A)=tan(2A) tan(2A)=2tanA/1-tan^2A =2(-√3)/(1-(-√3)^2 =-2√3/1+3 =-2√3/4 =-√3/2

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  1. Owlfred
    • 5 years ago
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    Hoot! You just asked your first question! Hang tight while I find people to answer it for you. You can thank people who give you good answers by clicking the 'Good Answer' button on the right!

  2. anonymous
    • 5 years ago
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    you can't call two different things the same variable and then add them like they are the same.

  3. anonymous
    • 5 years ago
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    there is an identity for tan(A+B) though

  4. anonymous
    • 5 years ago
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    thats what i thought. but when i did it as tan(A+B) which would be tanA+tanb/1-tanAtanB it did not correspond with the answer my teacher gave which is -√3/3.

  5. anonymous
    • 5 years ago
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    I think -sqrt(3)/3 is incorrect

  6. anonymous
    • 5 years ago
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    what did you get?

  7. anonymous
    • 5 years ago
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    -9√3+8√5/-13

  8. anonymous
    • 5 years ago
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    maple is saying that isn't right. Let me work the problem.. one sec.

  9. anonymous
    • 5 years ago
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    ok i got (-9sqrt(3)+8sqrt(5))/(-11)

  10. anonymous
    • 5 years ago
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    thats what maple got too

  11. anonymous
    • 5 years ago
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    ok so my numerator is right but my denominator is wrong. can you explain how you got the denominator?

  12. anonymous
    • 5 years ago
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    my denominator was initially 1+sqrt(3)*sqrt(5)/2, so i multiplied top and bottom by the conjugate: then in the denominator you get 1-15/4. In the numerator there was a common factor of 1/4 so i multiplied the denominator by 4: 4-15=-11

  13. anonymous
    • 5 years ago
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    ohhh never mind i got it. thanks soo much for your help!!!

  14. anonymous
    • 5 years ago
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    you're welcome :)

  15. anonymous
    • 5 years ago
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    are you a musician?

  16. anonymous
    • 5 years ago
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    yeah i play the cello&piano and i can carry a tune =) also how do i give you a medal for your answer?

  17. anonymous
    • 5 years ago
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    oh if you want you click "good answer" in line with my name on one of my posts: I play classical/jazz violin and guitar. I like cello and piano a lot.

  18. anonymous
    • 5 years ago
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    ohh thats great ! nice to meet a fellow musician =)

  19. anonymous
    • 5 years ago
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    well good luck with your math, talk to you later

  20. anonymous
    • 5 years ago
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    thank you !

  21. anonymous
    • 5 years ago
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    oh ok i got that. could you have used the quadratic formula to solve the equation?

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spraguer (Moderator)
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