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anonymous

  • one year ago

If Sin(x)+Cos(x)=5/4, What is Sin(2x) given that 0<x<pi/2

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  1. dan815
    • one year ago
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    |dw:1438557266598:dw|

  2. anonymous
    • one year ago
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    So Tan x=5/4? If so, Im confused on what to do next

  3. dan815
    • one year ago
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    sry wait

  4. dan815
    • one year ago
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    ignore those comments

  5. dan815
    • one year ago
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    sin(2x)= 2sin(x) cos(x) this is an identity

  6. dan815
    • one year ago
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    |dw:1438558276453:dw|

  7. dan815
    • one year ago
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    now solve for x

  8. anonymous
    • one year ago
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    Sorry to be a bother, but how'd you get it to match the identity like that?

  9. dan815
    • one year ago
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    i multiplied both sides by 2cosx

  10. dan815
    • one year ago
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    since that would make the left side equal to sin(2x)

  11. dan815
    • one year ago
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    now u end up with nice working equations

  12. dan815
    • one year ago
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    by divide both sides by cos(x)

  13. dan815
    • one year ago
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    ugh lemme think what can we do with this now

  14. dan815
    • one year ago
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    |dw:1438558934418:dw|

  15. dan815
    • one year ago
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    |dw:1438558970510:dw|

  16. dan815
    • one year ago
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    you gotta solve these 2 system of equations somehow

  17. anonymous
    • one year ago
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    Since the problem only asks for What Sin2x equals, wouldn't -2Cos^2(x)+5/2Cos(x) be correct?

  18. dan815
    • one year ago
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    well i guess, but are u sure they arent looking for value for x

  19. anonymous
    • one year ago
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    I just checked. They only want Sin2x=... Thank you so much

  20. dan815
    • one year ago
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    ok you're welcome!

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