esborrany circumferencies 6è

les tres fan el mateix calculen a partir del radi amb mes o menys decimals i alguna calcula la superfie també
http://easycalculation.com/area/circle.php
http://www.athropolis.com/popup/c-circ2.htm
http://www.basic-mathematics.com/circumference-calculator.html
http://www.calculatorsoup.com/calculators/geometry-plane/circle.php

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http://www.brainpop.com/math/geometry/

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http://www.glencoe.com/sec/math/studytools/cgi-bin/msgQuiz.php4?isbn=0-02-833052-8&chapter=7&lesson=7
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http://www.onlinemathlearning.com/geometry-math-games.html