Solution 4.1:3c

From Förberedande kurs i matematik 1

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In this right-angled triangle, the side of length 17 is the hypotenuse (it is the side which is opposite the right angle). The Pythagorean theorem then gives
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<center> [[Image:4_1_3c.gif]] </center>
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{{Displayed math||<math>17^2 = 8^2 + x^2</math>}}
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or
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{{Displayed math||<math>x^2 = 17^2 - 8^2\,\textrm{.}</math>}}
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We get
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{{Displayed math||<math>\begin{align}
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x &= \sqrt{17^2-8^2} = \sqrt{289-64} = \sqrt{225}\\[5pt]
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&= \sqrt{9\cdot 25} = \sqrt{3^2\cdot 5^2} = 3\cdot 5 = 15\,\textrm{.}
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\end{align}</math>}}

Current revision

In this right-angled triangle, the side of length 17 is the hypotenuse (it is the side which is opposite the right angle). The Pythagorean theorem then gives

\displaystyle 17^2 = 8^2 + x^2

or

\displaystyle x^2 = 17^2 - 8^2\,\textrm{.}

We get

\displaystyle \begin{align}

x &= \sqrt{17^2-8^2} = \sqrt{289-64} = \sqrt{225}\\[5pt] &= \sqrt{9\cdot 25} = \sqrt{3^2\cdot 5^2} = 3\cdot 5 = 15\,\textrm{.} \end{align}