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| 1. |
Prove that the ratio of the perimeter of two similar triangles is equal to the corresponding sides |
| Answer» Given\xa0{tex}\\triangle A B C{/tex}\xa0and\xa0{tex}\\triangle PQR{/tex}\xa0in Which BC= a, CA = b, AB = c and QR = p, RP = q, PQ = r.Also, {tex}\\triangle A B C \\sim \\triangle P Q R{/tex}To Prove\xa0{tex}\\frac { a } { p } = \\frac { b } { q } = \\frac { c } { r }{/tex}{tex}= \\frac { a + b + c } { p + q + r }{/tex}Proof Since\xa0{tex}\\triangle ABC{/tex}\xa0and\xa0{tex}\\triangle PQR{/tex}\xa0are similar, therefore their corresponding sides are proportional.{tex}\\therefore \\quad \\frac { a } { p } = \\frac { b } { q } = \\frac { c } { r } = k{/tex}\xa0(say) ...(i){tex}\\Rightarrow \\quad a = k p , b = k q{/tex}\xa0and\xa0{tex}c = k r{/tex}{tex}\\therefore \\quad \\frac { \\text { perimeter of } \\triangle A B C } { \\text { perimeter of } \\triangle P Q R }{/tex}{tex}= \\frac { a + b + c } { p + q + r }{/tex}{tex}= \\frac { k p + k q + k r } { p + q + r }{/tex}{tex}= \\frac { k ( p + q + r ) } { ( p + q + r ) } = k{/tex}\xa0...(ii)From (i) and (ii), we get{tex}\\frac { a } { p } = \\frac { b } { q } = \\frac { c } { r }{/tex}{tex}= \\frac { a + b + c } { p + q + r }{/tex}{tex}= \\frac { \\text { perimeter of } \\triangle A B C } { \\text { perimeter of } \\triangle P Q R }{/tex}\xa0[each equal to k]. | |