document.write( "Question 1171116: Hi\r
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document.write( "Andrew was given a rectangular cardboard 28cm by 16cm. How many right angle triangles 4cm high base 3cm could cut out. \r
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document.write( "Thanks\r
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Algebra.Com's Answer #796015 by ikleyn(52782)![]() ![]() You can put this solution on YOUR website! . \n" ); document.write( "Andrew was given a rectangular cardboard 28cm by 16cm. How many right angle triangles 4cm high base 3cm could cut out. \n" ); document.write( "~~~~~~~~~~~~~\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( "Two right angled triangles with the legs of 3 cm and 4 cm, placed hypotenuse to hypotenuse, form a 3x4-rectangle.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "Let's calculate how many such rectangles can be placed onto the 28x16 cm cardboard.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "We have two basic placements.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "One placement is to direct the 4-cm side of the rectangle along its 28 cm dimension.\r\n" ); document.write( "\r\n" ); document.write( "By doing this way, we have 28/4 = 7 rectanles in this direction and, OBVIOSLY, 5 rectangles in the perpendicular direction,\r\n" ); document.write( " (because 16/3 = 5.33 = 5 when rounded to the closest smaller integer).\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "In all, we have 7*5 = 35 rectangles and, hence, 35*2 = 70 right angled triangles at such placement.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "Next, consider another placement, directing the 4-cm side side along the 16-cm side of the cardboard.\r\n" ); document.write( "\r\n" ); document.write( "We have then the 3-cm side along the 28-cm side of the cardboard.\r\n" ); document.write( "\r\n" ); document.write( "By doing this way, we have 4 rectangles along the 16-cm side of the cardboard and, OBVIOUSLY, 9 rectangles along its 28 cm side \r\n" ); document.write( " (because 28/3 = 9.33 = 9 rounded to the closest smaller integer).\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "In all, we have 4*9 = 36 rectangles and, hence, 36*2 = 72 right angled triangles at such placement.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "Of these two opportunities, we chose the placement, which gives maximum numer of rectangles (36) and maximum number of triangles (72).\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "ANSWER. Maximum number of triangles is 72.\r\n" ); document.write( "\r \n" ); document.write( "\n" ); document.write( "Solved.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "----------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Such problems teachers give to young (advanced ?) students of 5th - 6th grades to check if they are able \n" ); document.write( "to think on self-standing basis and to teach them to solve such problems accurately (and to think accurately) \n" ); document.write( "on the self-standing manner.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The solution by @MathLover1, based on consideration the areas ONLY, gives an ESTIMATION ONLY \n" ); document.write( "for the maximum number of triangles from the top, but does not give the exact number of triangles.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The solution by @MathLover1 IS NOT what is expected.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Learn on how to solve such problems (and how to teach your students, if you are a teacher) - from my post.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |