Algebra

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Fomula: A=1/2(b1+b2)h

A=area of a trapezoid

b1=width at the top

b2-width at the bottom

h=height

A 7-foor tall trapezoid has 42 square feet of area. If is is 9 feet wide at the bottom, how far across is it at the top?

  • Algebra -

    I will set it up for you and you can simplify.

    A = 42

    h = 7

    b2 = 9

    I will plug and you can chug.

    42 = 1/2(b1 + 9)(7)

    Solve for b1, which is read "b sub one."

    Can you take it from here?

  • Algebra -

    Thank you for your response. I can set up and calculate. The book says I should be getting 3 feet as my answer. That is not what I am getting.

  • Algebra -

    Here it is:

    First multiply 7 x 1/2 = 7/2.

    We now have this equation:

    42 = 7/2(b1) + 9)

    Simplify the right side of the equation and the whole thing becomes


    42 = 7/2(b1) + 63/2

    Subtract 63/2 from 42.

    42 - 63/2 = 10_1/2

    We now have:

    10_1/2 = 7/2(b1)

    10_1/2 divided by 7/2 = b1

    3 feet = b1

    Done!

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