document.write( "Question 764136: If two angels of a triangle are acute angles,then the third angle is?\r
\n" );
document.write( "\n" );
document.write( "Less then the sum of the other two angles\r
\n" );
document.write( "\n" );
document.write( "Is an acute angle\r
\n" );
document.write( "\n" );
document.write( "Is an obtuse angle\r
\n" );
document.write( "\n" );
document.write( "Is the largest angle of the triangle \n" );
document.write( "
Algebra.Com's Answer #465222 by solver91311(24713)![]() ![]() You can put this solution on YOUR website! \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "All of the choices are possible, but none of them is certain.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Proof: Let angle A and angle B be the given acute angles and angle C be the third angle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "and\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "By definition of acute\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Since we can choose any value in that range for angles A and B, let's choose 89 degrees for each one.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Then the sum of the measures of the two angles is then 178 degrees. Since the sum of the three angles of any triangle is 180, Angle C must measure 2 degrees, which makes Angle C an acute angle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So far we have validated the first two answers and invalidated the last two.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now, let the measures of angle A and angle B each be 1 degree, making the measure of angle C 178 degrees.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "This situation invalidates the first two answers but validates the last two.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Therefore the fact that two of the angles of a triangle are acute tells you nothing substantive except that you actually have a triangle. In fact EVERY triangle has at least two acute angles. I'll leave the proof of that assertion as an exercise for the student.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "John \n" ); document.write( " \n" ); document.write( "My calculator said it, I believe it, that settles it \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " |