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)![]() ![]() You can put this solution on YOUR website! Use the cosine law for the longest side of the triangle: \n" ); document.write( " \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. \n" ); document.write( " |