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Math Help - can someone check my work thanks!!

  1. #1
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    Red face can someone check my work thanks!!

    Can someone please check my work thanks!!

    1) An angle with a negative rotation passes through the point (-5, 8). To the nearest degree, what is the measure of the angle?
    a) -238
    b)-148
    c) -122
    d) 58
    My answer is B -142

    2) For -180< 0 < -90, which of the primary trigonometric function is positive in this interval?
    A) Cos 0
    b) Tan 0
    c) Sin 0

    My answer is B Tan 0

    3) A central angle subtends an arc of 35cm. if the radius of the circle is 12 cm, what is the measure of the central angle to the nearest degree?
    A. 2.9
    B. 292
    C. 167
    D. 173
    My answer is A 2.9
    4) Are -5 (pi square) /9 and 5 (pi square) /9 coterminal angles?

    My answer:
    No they are not coterminal angles because it is not minuses or added by 360.


    5) what is the exact value of sin 5 (pi square) / 6?

    The exact value is



    Thanks in advance!!
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by bobs View Post
    Can someone please check my work thanks!!

    1) An angle with a negative rotation passes through the point (-5, 8). To the nearest degree, what is the measure of the angle?
    a) -238
    b)-148
    c) -122
    d) – 58
    My answer is B -142
    This is in the 2nd quadrant, so is -238 degrees

    2) For -180< 0 < -90, which of the primary trigonometric function is positive in this interval?
    A) Cos 0
    b) Tan 0
    c) Sin 0

    My answer is B Tan 0
    This is quadrant 3, so yest its tan.

    3) A central angle subtends an arc of 35cm. if the radius of the circle is 12 cm, what is the measure of the central angle to the nearest degree?
    A. 2.9
    B. 292
    C. 167
    D. 173
    My answer is A 2.9
    In radians this is 35/12 or in degrees 35/12*180/pi~=167 degrees.

    4) Are -5 (pi square) /9 and 5 (pi square) /9 coterminal angles?

    My answer:
    No they are not coterminal angles because it is not minuses or added by 360.
    This looks OK, but I am suspicious of the appearence of pi^2 in this
    and the next question, also are they supposed to be in degrees or radians?

    5) what is the exact value of sin 5 (pi square) / 6?

    The exact value is &#189;
    Not likely, also use more brackets to make this less ambiguous, and clarify
    the angle measure in use. As it is I would be supprised if it had an exact
    value (in the sense intended in the question)

    RonL
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  3. #3
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    sorry....

    5) what is the exact value of sin 5 (pi square) / 6?
    sorry is is multipule choice
    A. 1/2
    B. -1/2
    C. Square root (3) / 2
    D. - Square root (3) / 2

    okay since it is not A right I think the exact value is B -1/2 is that right??
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  4. #4
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    Quote Originally Posted by bobs View Post
    5) what is the exact value of sin 5 (pi square) / 6?
    sorry is is multipule choice
    A. 1/2
    B. -1/2
    C. Square root (3) / 2
    D. - Square root (3) / 2

    okay since it is not A right I think the exact value is B -1/2 is that right??
    I do not think there is a way to get,
    \sin \frac{5\pi^2}{6}
    Unless you want,
    \sin \frac{5\pi}{6}
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  5. #5
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    okay...

    No sorry I want this one...
    \sin \frac{5\pi}{6}[/QUOTE]

    sorry for the mix up!!
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  6. #6
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    Quote Originally Posted by bobs View Post
    No sorry I want this one...
    \sin \frac{5\pi}{6}
    sorry for the mix up!![/QUOTE]

    That is,
    \frac{5(180)^o}{6}
    Thus,
    150^o

    In the second quadrant.
    Use the identity,
    \sin (180^o-x)=\sin x
    Thus,
    \sin 150^o=\sin (180^o-30^o)=\sin 30^o=\frac{1}{2}
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