Anonymous
Anonymous asked in Science & MathematicsMathematics · 3 weeks ago

Calling people who like to do maths!?

We have never been taught this and we have to finish the paper. Help appreciated! 😊

Update:

Its pythagoras btw

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15 Answers

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  • 2 weeks ago

    It is Pythagoras. How do you know that if you weren't taught?

    13^2 + x^2 = 18^2

    solving for x I get x^2 = 18^2 - 13^2 =155

    so x = 12.4

  • Como
    Lv 7
    2 weeks ago

    x² + 13² = 18²

    x² = 18² - 13²

    x² = 155

    x = √155

    x = 12•4

  • 2 weeks ago

    Oh dear hope you get your answer

  • D g
    Lv 7
    2 weeks ago

    If you know it's Pythagoras then you should be able to solve it 

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  • 3 weeks ago

    hehe I love non-americans and saying maths, and b/c you asked very nicely

    Pythagoras is a^2 + b^2 = c^2 where c is the hypotenuse and a and b are the legs of a right triangle. the hypotenuse is the long side and a and b are the shorter sides. 

    so your x is a leg, let's call it b.

    a^2 + b^2 = c^2

    13^2 + b^2 = 18^2

    b^2 = 18^2 - 13^2

    b = sqrt(18^2 - 13^2)

    plug that sucker in! and according to this other guy, it's 12.4

    • Tom S
      Lv 7
      2 weeks agoReport

      Are you being defensive, or defencive?

  • 3 weeks ago

    x^2 + 13^2 = 18^2

    x^2 = 18^2 - 13^2

    x = sqrt (5*31) = sqrt 155 = 12.45

  • 3 weeks ago

    I presume that YOU do not "like to do math".  I do not believe that you have not been taught how to use the Pythagoras theorem.

  • Ian H
    Lv 7
    3 weeks ago

    You probably have been taught the Pythagorean Theorem but perhaps you forgot about it or it did not make a big impression or maybe you feel unsure about it. This problem is easier than you think. Difference of two squares. 

    x^2 = 18^2 – 13^2 = (18 – 13) * (18 + 13) = 5*31 = 155 

    Using a calculator, x = √(155) ~ 12.4498995 ..... 

    That is just below 12.45 so, to 3 significant figures x ~ 12.4 

  • 3 weeks ago

    You really haven't been taught the Pythagorean Theorem? You aren't familiar with:

    a² + b² = c²

    a and b are the lengths of the legs of the right triangle.

    c is the hypotenuse.

    In your case:

    a = x

    b = 13

    c = 18

    So write:

    x² + 13² = 18²

    x² + 169 = 324

    x² = 324 - 169

    x² = 155

    x = √155

    It seems they want an approximate answer and if we round to 3 significant figures, that is 12.4 cm. 

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    • Puzzling
      Lv 7
      2 weeks agoReport

      Don't forget to go back and award Best Answer.

  • 3 weeks ago

    Since you know this is a right triangle, you can use Pythagorean Theorem to solve for an unknown side given that you know the other two:

    a² + b² = c²

    13² + x² = 18²

    169 + x² = 324

    x² = 155

    x = 12.5 cm (rounded to 3SF)

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