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lilsis76

  • 3 years ago

is x=15 degrees a solution of (( sqrt3)/3) cos2x+sin2x=1? how can i figure this out?

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  1. campbell_st
    • 3 years ago
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    just substitute x = 15 into each trig ratio and use the exact angle identities below |dw:1352142650262:dw| if x =15 then 2x = 30.... use the exact values from the triangle above for cos2(15) = cos(30) ans sin2(15) = sin(30)

  2. lilsis76
    • 3 years ago
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    how did you figure the triangle? even i didnt get or understand how to do that

  3. lilsis76
    • 3 years ago
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    is the cos sqrt 3 / 2 and the sin 1/2?

  4. campbell_st
    • 3 years ago
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    its called the an exact value triangle and its usually taught during a topic on trigonometry. thats correct now substitute those values to show that you will get 1 as the answer,

  5. lilsis76
    • 3 years ago
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    okay let me try it. hold on

  6. lilsis76
    • 3 years ago
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    |dw:1352143377873:dw|

  7. lilsis76
    • 3 years ago
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    is this right? so it doesnt equal 1

  8. campbell_st
    • 3 years ago
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    not quite |dw:1352143232742:dw|

  9. lilsis76
    • 3 years ago
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    so it doesnt equal 1 still. right?

  10. campbell_st
    • 3 years ago
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    yes it does you need to check the 1st part |dw:1352143563524:dw|

  11. lilsis76
    • 3 years ago
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    hold on let me try again, i wrote all sloppy

  12. lilsis76
    • 3 years ago
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    |dw:1352144119351:dw|

  13. campbell_st
    • 3 years ago
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    your question says |dw:1352143923416:dw|

  14. lilsis76
    • 3 years ago
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    yes

  15. campbell_st
    • 3 years ago
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    substituting the exact values gives |dw:1352143978828:dw|

  16. lilsis76
    • 3 years ago
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    okay i see the 2x, is basically that value of cos that is the sqrt 3 /2

  17. campbell_st
    • 3 years ago
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    thats right it x = 15 2x = 30 so you are using cos(30) and sin(30) which are known as exact values.

  18. lilsis76
    • 3 years ago
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    |dw:1352144487645:dw|

  19. campbell_st
    • 3 years ago
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    no |dw:1352144327997:dw|

  20. lilsis76
    • 3 years ago
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    okay so the answer is 1/2, so the equation does not equal 1

  21. campbell_st
    • 3 years ago
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    I'll write it again |dw:1352144410590:dw|

  22. lilsis76
    • 3 years ago
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    okay, so i would cross multiply to the the 6/6 to equal 1?

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