document.write( "Question 1065772: A triangular pyramid has a lateral surface of 225 square centimeters. If the height of the pyramid is greater than 12 centimeters and the base has nine equal sides, what are whole-number possibilities for the height and width of each triangular face? \n" ); document.write( "
Algebra.Com's Answer #680938 by Theo(13342)![]() ![]() You can put this solution on YOUR website! lateral surface area doesn't include the area of the base. \n" ); document.write( "if there are 9 equal sides, then there are 9 equal triangles. \n" ); document.write( "that means the area of each triangle is 25 square centimeters. \n" ); document.write( "the formula for the area of a triangle is 1/2 * b * h. \n" ); document.write( "you get 1/2 * b * h = 25 \n" ); document.write( "multiply both sides of this equation by 2 and you get b * h = 50 \n" ); document.write( "divide both sides of this equation by h and you get b = 50 / h \n" ); document.write( "since b > 12, then 50 / h > 12. \n" ); document.write( "multiply both sides of this equation by h to get 50 > 12 * h. \n" ); document.write( "looks like h is a multiple of 12 and can be 1, 2, 3, or 4. \n" ); document.write( "it can't be 5 because 12 * 5 = 60 > 50. \n" ); document.write( "to test these out, use the formula of 25 = 1/2 * b * h and multiply both sides of it by 2 to get 50 = b * h. \n" ); document.write( "if b = 1, then h = 50 > 12 which is a whole number. \n" ); document.write( "if b = 2, then h = 25 > 12 which is a whole number. \n" ); document.write( "if b = 3, then h = 15 and 5/15 > 12 but is not a whole number. \n" ); document.write( "if b = 4, then h = 12 and 2/12 > 12 but is not a whole number. \n" ); document.write( "if b = 5, then h = 10 which is smaller than 12. \n" ); document.write( "my guess is that the base can either be 1 or 2. \n" ); document.write( "when 1, the height is 50. \n" ); document.write( "when 2, the height is 25. \n" ); document.write( "the area of each triangle is always 25. \n" ); document.write( "the lateral area is always 225.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |