2. The sides of certain triangles are given below. Determine which of them are right triangles.
2. The sides of certain triangles are given below. Determine which of them are right triangles.

    \[\begin{array}{*{35}{l}}</strong> <!-- /wp:paragraph --> <!-- wp:paragraph --> <strong>   \left( \mathbf{i} \right)\text{ }\mathbf{a}\text{ }=\text{ }\mathbf{7}\text{ }\mathbf{cm},\text{ }\mathbf{b}\text{ }=\text{ }\mathbf{24}\text{ }\mathbf{cm}\text{ }\mathbf{and}\text{ }\mathbf{c}\text{ }=\text{ }\mathbf{25}\text{ }\mathbf{cm}  \\</strong> <!-- /wp:paragraph --> <!-- wp:paragraph --> <strong>   \left( \mathbf{ii} \right)\text{ }\mathbf{a}\text{ }=\text{ }\mathbf{9}\text{ }\mathbf{cm},\text{ }\mathbf{b}\text{ }=\text{ }\mathbf{16}\text{ }\mathbf{cm}\text{ }\mathbf{and}\text{ }\mathbf{c}\text{ }=\text{ }\mathbf{18}\text{ }\mathbf{cm}  \\</strong> <!-- /wp:paragraph --> <!-- wp:paragraph --> <strong>   \left( \mathbf{iii} \right)\text{ }\mathbf{a}\text{ }=\text{ }\mathbf{1}.\mathbf{6}\text{ }\mathbf{cm},\text{ }\mathbf{b}\text{ }=\text{ }\mathbf{3}.\mathbf{8}\text{ }\mathbf{cm}\text{ }\mathbf{and}\text{ }\mathbf{c}\text{ }=\text{ }\mathbf{4}\text{ }\mathbf{cm}  \\</strong> <!-- /wp:paragraph --> <!-- wp:paragraph --> <strong>   \left( \mathbf{iv} \right)\text{ }\mathbf{a}\text{ }=\text{ }\mathbf{8}\text{ }\mathbf{cm},\text{ }\mathbf{b}\text{ }=\text{ }\mathbf{10}\text{ }\mathbf{cm}\text{ }\mathbf{and}\text{ }\mathbf{c}\text{ }=\text{ }\mathbf{6}\text{ }\mathbf{cm}  \\</strong> <!-- /wp:paragraph --> <!-- wp:paragraph --> <strong>\end{array}\]

                                                      

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Solutions:

(i) Given,

    \[\begin{array}{*{35}{l}} <!-- /wp:paragraph --> <!-- wp:paragraph -->    a\text{ }=\text{ }7\text{ }cm,\text{ }b\text{ }=\text{ }24\text{ }cm\text{ }and\text{ }c\text{ }=\text{ }25\text{ }cm  \\ <!-- /wp:paragraph --> <!-- wp:paragraph -->    \therefore {{a}^{2}}~=\text{ }49,\text{ }{{b}^{2}}~=\text{ }576\text{ }and\text{ }{{c}^{2}}~=\text{ }625  \\ <!-- /wp:paragraph --> <!-- wp:paragraph -->    Since,\text{ }{{a}^{2}}~+\text{ }{{b}^{2}}~=\text{ }49\text{ }+\text{ }576\text{ }=\text{ }625\text{ }=\text{ }{{c}^{2}}  \\ <!-- /wp:paragraph --> <!-- wp:paragraph --> \end{array}\]

                                                        

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Then, by converse of Pythagoras theorem

The given sides are of a right triangle.

(ii) Given,

    \[\begin{array}{*{35}{l}} <!-- /wp:paragraph --> <!-- wp:paragraph -->    a\text{ }=\text{ }9\text{ }cm,\text{ }b\text{ }=\text{ }16\text{ }cm\text{ }and\text{ }c\text{ }=\text{ }18\text{ }cm  \\ <!-- /wp:paragraph --> <!-- wp:paragraph -->    \therefore {{a}^{2}}~=\text{ }81,\text{ }{{b}^{2}}~=\text{ }256\text{ }and\text{ }{{c}^{2}}~=\text{ }324  \\ <!-- /wp:paragraph --> <!-- wp:paragraph -->    Since,\text{ }{{a}^{2}}~+\text{ }{{b}^{2}}~=\text{ }81\text{ }+\text{ }256\text{ }=\text{ }337\text{ }\ne \text{ }{{c}^{2}}  \\ <!-- /wp:paragraph --> <!-- wp:paragraph --> \end{array}\]

                                                        

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Then, by converse of Pythagoras theorem

The given sides cannot be of a right triangle.

(iii) Given,

    \[\begin{array}{*{35}{l}} <!-- /wp:paragraph --> <!-- wp:paragraph -->    a\text{ }=\text{ }1.6\text{ }cm,\text{ }b\text{ }=\text{ }3.8\text{ }cm\text{ }and\text{ }C\text{ }=\text{ }4\text{ }cm  \\ <!-- /wp:paragraph --> <!-- wp:paragraph -->    \therefore {{a}^{2}}~=\text{ }2.56,\text{ }{{b}^{2}}~=\text{ }14.44\text{ }and\text{ }{{c}^{2}}~=\text{ }16  \\ <!-- /wp:paragraph --> <!-- wp:paragraph --> \end{array}\]

                                                        

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Since,

    \[{{a}^{2}}~+\text{ }{{b}^{2}}~=\text{ }2.56\text{ }+\text{ }14.44\text{ }=\text{ }17\text{ }\ne \text{ }{{c}^{2}}\]

Then, by converse of Pythagoras theorem

The given sides cannot be of a right triangle.

(iv) Given,

    \[\begin{array}{*{35}{l}} <!-- /wp:paragraph --> <!-- wp:paragraph -->    a\text{ }=\text{ }8\text{ }cm,\text{ }b\text{ }=\text{ }10\text{ }cm\text{ }and\text{ }C\text{ }=\text{ }6\text{ }cm  \\ <!-- /wp:paragraph --> <!-- wp:paragraph -->    \therefore {{a}^{2}}~=\text{ }64,\text{ }{{b}^{2}}~=\text{ }100\text{ }and\text{ }{{c}^{2}}~=\text{ }36  \\ <!-- /wp:paragraph --> <!-- wp:paragraph --> \end{array}\]

                                                        

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Since,

    \[{{a}^{2}}~+\text{ }{{c}^{2}}~=\text{ }64\text{ }+\text{ }36\text{ }=\text{ }100\text{ }=\text{ }{{b}^{2}}\]

Then, by converse of Pythagoras theorem

The given sides are of a right triangle