Re: Repère dans le plan trouver des coordonées : Urgent!
Posté : sam. 12 nov. 2016 10:20
Je voudrai une aide sur le 3 de ce même exercice si possible svp
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Bonjour je ne comprends pas d'ou sort le 5a ?sos-math(21) a écrit :Bonjour,
d'après les post précédents, tu as
\(BA^2=20\) ; \(BM^2=4+(2,5-a)^2\) et \(AM^2=16+(a+1,5)^2\).
L'identité de Pythagore mène à <span class="MathJax_Preview" style="color: inherit; display: none;"></span><span class="MathJax" id="MathJax-Element-15-Frame" tabindex="0" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi ... sup></math>" role="presentation" style="position: relative;"><nobr aria-hidden="true"><span class="math" id="MathJax-Span-254" style="width: 10.694em; display: inline-block;"><span style="display: inline-block; position: relative; width: 9.228em; height: 0px; font-size: 116%;"><span style="position: absolute; clip: rect(1.039em 1009.23em 2.504em -999.996em); top: -2.151em; left: 0em;"><span class="mrow" id="MathJax-Span-255"><span class="mi" id="MathJax-Span-256" style="font-family: MathJax_Math-italic;">B</span><span class="msubsup" id="MathJax-Span-257"><span style="display: inline-block; position: relative; width: 1.211em; height: 0px;"><span style="position: absolute; clip: rect(3.022em 1000.69em 4.228em -999.996em); top: -3.961em; left: 0em;"><span class="mi" id="MathJax-Span-258" style="font-family: MathJax_Math-italic;">A</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span><span style="position: absolute; top: -4.306em; left: 0.78em;"><span class="mn" id="MathJax-Span-259" style="font-size: 70.7%; font-family: MathJax_Main;">2</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span></span></span><span class="mo" id="MathJax-Span-260" style="font-family: MathJax_Main; padding-left: 0.263em;">+</span><span class="mi" id="MathJax-Span-261" style="font-family: MathJax_Math-italic; padding-left: 0.263em;">B</span><span class="msubsup" id="MathJax-Span-262"><span style="display: inline-block; position: relative; width: 1.556em; height: 0px;"><span style="position: absolute; clip: rect(3.022em 1001.04em 4.228em -999.996em); top: -3.961em; left: 0em;"><span class="mi" id="MathJax-Span-263" style="font-family: MathJax_Math-italic;">M<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.091em;"></span></span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span><span style="position: absolute; top: -4.306em; left: 1.125em;"><span class="mn" id="MathJax-Span-264" style="font-size: 70.7%; font-family: MathJax_Main;">2</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span></span></span><span class="mo" id="MathJax-Span-265" style="font-family: MathJax_Main; padding-left: 0.263em;">=</span><span class="mi" id="MathJax-Span-266" style="font-family: MathJax_Math-italic; padding-left: 0.263em;">A</span><span class="msubsup" id="MathJax-Span-267"><span style="display: inline-block; position: relative; width: 1.556em; height: 0px;"><span style="position: absolute; clip: rect(3.022em 1001.04em 4.228em -999.996em); top: -3.961em; left: 0em;"><span class="mi" id="MathJax-Span-268" style="font-family: MathJax_Math-italic;">M<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.091em;"></span></span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span><span style="position: absolute; top: -4.306em; left: 1.125em;"><span class="mn" id="MathJax-Span-269" style="font-size: 70.7%; font-family: MathJax_Main;">2</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 2.159em;"></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.195em; border-left: 0px solid; width: 0px; height: 1.305em;"></span></span></nobr><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi ... an><script type="math/tex" id="MathJax-Element-15">BA^2+BM^2=AM^2</script>.
Donc cela donne : \(20 + 4+(2,5-a)^2 = 16+(a+1,5)^2\) soit <span class="MathJax_Preview" style="color: inherit; display: none;"></span><span class="MathJax" id="MathJax-Element-16-Frame" tabindex="0" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn ... /mo></math>" role="presentation" style="position: relative;"><nobr aria-hidden="true"><span class="math" id="MathJax-Span-270" style="width: 15.263em; display: inline-block;"><span style="display: inline-block; position: relative; width: 13.108em; height: 0px; font-size: 116%;"><span style="position: absolute; clip: rect(1.211em 1013.02em 2.763em -999.996em); top: -2.323em; left: 0em;"><span class="mrow" id="MathJax-Span-271"><span class="mn" id="MathJax-Span-272" style="font-family: MathJax_Main;">24</span><span class="mo" id="MathJax-Span-273" style="font-family: MathJax_Main; padding-left: 0.263em;">+</span><span class="mn" id="MathJax-Span-274" style="font-family: MathJax_Main; padding-left: 0.263em;">6</span><span class="mo" id="MathJax-Span-275" style="font-family: MathJax_Main;">,</span><span class="mn" id="MathJax-Span-276" style="font-family: MathJax_Main; padding-left: 0.177em;">25</span><span class="mo" id="MathJax-Span-277" style="font-family: MathJax_Main; padding-left: 0.263em;">−</span><span class="mn" id="MathJax-Span-278" style="font-family: MathJax_Main; padding-left: 0.263em;">5</span><span class="mi" id="MathJax-Span-279" style="font-family: MathJax_Math-italic;">a</span><span class="mo" id="MathJax-Span-280" style="font-family: MathJax_Main; padding-left: 0.263em;">+</span><span class="msubsup" id="MathJax-Span-281" style="padding-left: 0.263em;"><span style="display: inline-block; position: relative; width: 0.953em; height: 0px;"><span style="position: absolute; clip: rect(3.28em 1000.52em 4.228em -999.996em); top: -3.961em; left: 0em;"><span class="mi" id="MathJax-Span-282" style="font-family: MathJax_Math-italic;">a</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span><span style="position: absolute; top: -4.306em; left: 0.522em;"><span class="mn" id="MathJax-Span-283" style="font-size: 70.7%; font-family: MathJax_Main;">2</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span></span></span><span class="mo" id="MathJax-Span-284" style="font-family: MathJax_Main; padding-left: 0.263em;">=</span><span class="mn" id="MathJax-Span-285" style="font-family: MathJax_Main; padding-left: 0.263em;">16</span><span class="mo" id="MathJax-Span-286" style="font-family: MathJax_Main;">+</span><span class="mo" id="MathJax-Span-287" style="font-family: MathJax_Main;">.</span><span class="mo" id="MathJax-Span-288" style="font-family: MathJax_Main; padding-left: 0.177em;">.</span><span class="mo" id="MathJax-Span-289" style="font-family: MathJax_Main; padding-left: 0.177em;">.</span></span><span style="display: inline-block; width: 0px; height: 2.332em;"></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.295em; border-left: 0px solid; width: 0px; height: 1.405em;"></span></span></nobr><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mn ... an><script type="math/tex" id="MathJax-Element-16">24+6,25-5a+a^2=16+...</script> : je te laisse développer le deuxième carré et tu dois avoir un <span class="MathJax_Preview" style="color: inherit; display: none;"></span><span class="MathJax" id="MathJax-Element-17-Frame" tabindex="0" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><ms ... sup></math>" role="presentation" style="position: relative;"><nobr aria-hidden="true"><span class="math" id="MathJax-Span-290" style="width: 1.125em; display: inline-block;"><span style="display: inline-block; position: relative; width: 0.953em; height: 0px; font-size: 116%;"><span style="position: absolute; clip: rect(-0.082em 1000.95em 1.297em -999.996em); top: -1.03em; left: 0em;"><span class="mrow" id="MathJax-Span-291"><span class="msubsup" id="MathJax-Span-292"><span style="display: inline-block; position: relative; width: 0.953em; height: 0px;"><span style="position: absolute; clip: rect(3.28em 1000.52em 4.228em -999.996em); top: -3.961em; left: 0em;"><span class="mi" id="MathJax-Span-293" style="font-family: MathJax_Math-italic;">a</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span><span style="position: absolute; top: -4.306em; left: 0.522em;"><span class="mn" id="MathJax-Span-294" style="font-size: 70.7%; font-family: MathJax_Main;">2</span><span style="display: inline-block; width: 0px; height: 3.97em;"></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 1.039em;"></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.095em; border-left: 0px solid; width: 0px; height: 1.205em;"></span></span></nobr><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><ms ... an><script type="math/tex" id="MathJax-Element-17">a^2</script> de chaque côté, ils s'éliminent donc.
Je te laisse poursuivre
sos-math(21) a écrit :Bonjour,
d'après les post précédents, tu as
\(BA^2=20\) ; \(BM^2=4+(2,5-a)^2\) et \(AM^2=16+(a+1,5)^2\).
L'identité de Pythagore mène à \(BA^2+BM^2=AM^2\).
Donc cela donne : \(20 + 4+(2,5-a)^2 = 16+(a+1,5)^2\) soit \(24+6,25-5a+a^2=16+...\) : je te laisse développer le deuxième carré et tu dois avoir un \(a^2\) de chaque côté, ils s'éliminent donc.
Je te laisse poursuivre
Tu simplifies par a²matthieu a écrit :Oui apres cela donne
30,25-5a+a² = 18,25+3a+a² mais je ne sais pas quoi faire ensuite