document.write( "Question 382794: If a triangle has the measures 4,7 and 9 is it an acute, obtuse or right? \n" ); document.write( "
Algebra.Com's Answer #271194 by robertb(5830)\"\" \"About 
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Use the cosine law for the longest side of the triangle:
\n" ); document.write( "\"9%5E2+=+4%5E2+%2B+7%5E2+-+2%2A4%2A7cosA\", where A is the angle opposite the side of length 9.
\n" ); document.write( "81 = 16 + 49 - 56cosA;
\n" ); document.write( "16 = -56cosA;
\n" ); document.write( "cosA = -16/56 = -2/7;
\n" ); document.write( "A = 106.6 degrees (approximately)
\n" ); document.write( "Therefore the triangle is an obtuse triangle.
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