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Math Help - computing areas and perimeters of simple figures and other stuff

  1. #1
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    computing areas and perimeters of simple figures and other stuff

    i dont understand these problemss.....please help me on them i got a summer packet and i dont understand almost none of the problemsssanyway here are the problems



    if the area of a circle is 64pi, then what is the circumfrence?


    if the minute hand of a clock moves 45 degrees, how many minutes of time have passed?





    a triangle of height 5 and base 4 has an area exactly 1/3 that of a rectangle with height 5 . what is the width of the rectangle?











    here are some other problems i dont understand..






    it says : determine a table of values for the domain of integers within
    -6< x< 6


    then it says :5x+3y=26


    and it has another problem

    3x-3y=27
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  2. #2
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    The area of a circle= \pi r^2 and the circumference= 2\pi r so set 64= pi r^2 solve for r anf plug into the circumference formula

    I'm not sure why you're having a problem with the second one, draw a picture, but here's a hint
    If the minute hand moves 30 minutes, it has moved 180 degrees, if it moves 15 minutes, then it moved 90 degrees


    Area of triangle= \frac{1}{2}base*height
    Area of rectangle= base*height

    So \frac{1}{2}(5)(5)=\frac{1}{3}5x

    The last problem is just asking for the y values of those equations when x=-5,-4,-3....,3,4,5
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  3. #3
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    Talking

    Quote Originally Posted by student897 View Post
    if the area of a circle is 64pi, then what is the circumfrence?
    Look up (and re-memorize) the formulas for the area A and the circumference C of a circle with radius r. Plug the given value into the appropriate formula, and solve for the value of r. Then plug this into the other formula to find the required value.

    Quote Originally Posted by student897 View Post
    if the minute hand of a clock moves 45 degrees, how many minutes of time have passed?
    Review the concept of "degrees" (in particular, how many degrees are in a circle), and then look at an analog (that is, non-digital) clock. Count the minutes.

    Quote Originally Posted by student897 View Post
    a triangle of height 5 and base 4 has an area exactly 1/3 that of a rectangle with height 5 . what is the width of the rectangle?
    Look up (and re-memorize) the formulas for the areas A of a triangle with base b and height h and of a rectangle with length L and width w. Plug the given values into the appropriate formula.

    Then note that, if the triangle is one-third of the rectangle, then the rectangle is three times of the triangle. Plug this, and the given value, into the other formula, and solve for the required value.

    Quote Originally Posted by student897 View Post
    it says : determine a table of values for the domain of integers within -6< x< 6 then it says :5x+3y=26
    Look up what "integers" are. Then review how to evaluate expressions. In this case, you'll be evaluating "5x + 3y = 26" for given values of x, and then solving for the corresponding values of y. Then you'll make a table, or chart, listing these pairs of values.

    Quote Originally Posted by student897 View Post
    3x-3y=27
    Lacking instructions for this exercise, I'm afraid I cannot advise. Sorry.
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  4. #4
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    Quote Originally Posted by student897 View Post
    i dont understand these problemss.....please help me on them i got a summer packet and i dont understand almost none of the problemsssanyway here are the problems



    if the area of a circle is 64pi, then what is the circumfrence?

    \pi r^2=64\pi , calculate r , then put it into S=2\pi r

    if the minute hand of a clock moves 45 degrees, how many minutes of time have passed?

    45/360x60=...


    a triangle of height 5 and base 4 has an area exactly 1/3 that of a rectangle with height 5 . what is the width of the rectangle?


    1/2(5)(4)=1/3(5w) , calculate w where w is width .








    here are some other problems i dont understand..






    it says : determine a table of values for the domain of integers within
    -6< x< 6


    then it says :5x+3y=26

    y=(26-5x) / 3 , so within the domain of -6<x<6 , what would the y's be?

    Then you will need to substitute one by one , ie -6 , -5 , -4 , ... , 6


    and it has another problem

    3x-3y=27

    Same method .
    .
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  5. #5
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    i understand now.. =]
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  6. #6
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    Why did you not understand BEFORE? Miss classes? Poor teacher?
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  7. #7
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    Quote Originally Posted by Wilmer View Post
    Why did you not understand BEFORE? Miss classes? Poor teacher?



    you are supposed to be posting helpful answers not asking me questions about my own personal life.
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  8. #8
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    The questions I asked are important: knowing whether you're a student
    or learning on your own makes a difference in how some of us will answer.
    However, I promise not to answer any more of yours. Good luck.
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  9. #9
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    umm ok do whatever u wanttt??
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