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Jen asked in Science & MathematicsMathematics · 10 years ago

Geometry: Need help finding angles of a quadrilateral?!?

The angles are EFGH

E= 8x-10

F= x^2+10

G= 2x+30

H= x^2+2x+10

I have the answers, I just don't know how to solve it. Can't seem to remember this at all.

4 Answers

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  • Anonymous
    10 years ago
    Favorite Answer

    Add up the angles to 360°.....

    8x - 10 + x² + 10 + 2x + 30 + x² + 2x + 10 = 360

    Then, solve for x to get...

    2x² + 12x + 40 = 360

    2x² + 12x - 320 = 0

    2(x² + 6x - 160) = 0

    2(x - 10)(x + 16) =

    x = 10

    Hence, the angles are...

    E = 70°

    F = 110°

    G = 50°

    H = 130°

    I hope this helps!

    Source(s): Σ
  • 10 years ago

    You also know that the angles add up to 360 degrees....

    So, E + F + G + H = 360

    So, 8x - 10 + x^2 + 10 + 2x + 30 + x^2 + 2x + 10 = 360

    ==> 2x^2 + 12x + 40 = 360

    ==> 2x^2 + 12x - 320 = 0

    ==> x^2 + 6x - 160 = 0

    Will leave the rest to you....

  • 10 years ago

    well all the angles of a quadrilateral add up to 360. So 8x-10+x^2+10+2x+30+x^2+2x+10=360

    2x^2+12x+40=360

    2x^2+12x-320=0

    2(x^2+6x-160)=0

    2(x-10)(x+16)=0

    so x=10 or x=-16 but can't be negative so x=10

    plug that x in.

    E=8*10-10 or 70

    etc....

    Source(s): im a math major
  • 10 years ago

    Well then the sum of the angles would be equal to 360;

    8x-10+x^2+10+2x+30+x^2+2x+10=360

    2x^2+14x+40=360

    2x^2+14x-320=0

    2(x^2+7x-160)=0

    -7+/- sqrt(49-4(1)(-160)=x

    -7+/- sqrt(689)

    -7+ 26.248 -7-26.248

    x=19.24 x=-33.248

    only 19.24 makes sense because -33 cannot be a measurement is a positive plane.

    DISREGARD THE ANSWER BEFORE MINE ONE OF THE 2x's WAS NOT ADDED

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