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[attach]124547[/attach] ============================================================ Forse doveva essere impostata con la parentesi all'inizio, quindi: small (cos dfrac { pi }{6}-cos dfrac { pi }{4})(sin dfrac { pi }{3}+sin dfrac { pi }{4})-tan^2( dfrac { pi }{3})=$ small = (cos30°-cos45°)(sin60°+sin45°)-tan^2(60°)=$ small = ( dfrac { sqrt 3}{2}- dfrac { sqrt 2}{2})( dfrac { sqrt 3}{2}+ dfrac { sqrt 2}{2})-( sqrt 3)^2 =$ small = dfrac {3}{4}+ dfrac { sqrt {3·2}}{4}- dfrac { sqrt {2·3}}{4}- dfrac { cancel 2^1}{ cancel 4_2}-3 =$ small = dfrac {3}{4}+ cancel { dfrac { sqrt {6}}{4}}- cancel { dfrac { sqrt {6}}{4}}- dfrac {1}{2}-3 =$ small = dfrac {3}{4}- dfrac {1}{2}-3 =$ small = dfrac {3-2-12}{4} =$ small = - dfrac {11}{4} $

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Forse doveva essere impostata con la parentesi all'inizio, quindi:

$\small \left(cos\dfrac{\pi}{6}-cos\dfrac{\pi}{4}\right)\left(sin\dfrac{\pi}{3}+sin\dfrac{\pi}{4}\right)-tan^2\left(\dfrac{\pi}{3}\right)=$

$\small = \left(cos30°-cos45°\right)\left(sin60°+sin45°\right)-tan^2\left(60°\right)=$

$\small = \left(\dfrac{\sqrt3}{2}-\dfrac{\sqrt2}{2}\right)\left(\dfrac{\sqrt3}{2}+\dfrac{\sqrt2}{2}\right)-\left(\sqrt3\right)^2 =$

$\small = \dfrac{3}{4}+\dfrac{\sqrt{3·2}}{4}-\dfrac{\sqrt{2·3}}{4}-\dfrac{\cancel2^1}{\cancel4_2}-3 =$

$\small = \dfrac{3}{4}+\cancel{\dfrac{\sqrt{6}}{4}}-\cancel{\dfrac{\sqrt{6}}{4}}-\dfrac{1}{2}-3 =$

$\small = \dfrac{3}{4}-\dfrac{1}{2}-3 =$

$\small = \dfrac{3-2-12}{4} =$

$\small = -\dfrac{11}{4} $

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