document.write( "Question 96231: Help again! It seems there are different ways to figure out problems for rectangles, squares, and triangles. Is there a different formula for all of them. The questions I'm working with give me the perimeter I have to figure out the dimensions. I FEEL SO OVERWHELMED!\r
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document.write( "ex. A square has a perimeter of 28 feet. Find the length of each side.\r
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document.write( "ex. A triangle has a perimeter of 23 inches. The medium side is 3 inches more than the shortest side, and the longest side is twice the shortest side. Find the shortest side. \n" );
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Algebra.Com's Answer #70053 by bucky(2189)![]() ![]() ![]() You can put this solution on YOUR website! Whenever you feel overwhelmed, you should always try to go back to the basic things you \n" ); document.write( "have learned. For example, these two problems involve perimeters. You should know that, by \n" ); document.write( "definition, the perimeter of a geometric figure is just the sum of the lengths of all the sides. \n" ); document.write( ". \n" ); document.write( "The first problem involves the perimeter and a square. What do you know about squares? A square \n" ); document.write( "is a special case of a rectangle. It has four sides and 4 angles of 90 degrees. In addition, \n" ); document.write( "what makes a square different from most rectangles? You probably know that all the sides \n" ); document.write( "of a square are equal. Let's use this basic information to solve the first problem. \n" ); document.write( ". \n" ); document.write( "Since the perimeter of a four sided figure is the sum of the lengths of the four sides, we \n" ); document.write( "can write an equation: \n" ); document.write( ". \n" ); document.write( "P = a + b + c + d \n" ); document.write( ". \n" ); document.write( "in which P represents the perimeter and a, b, c, and d represent the 4 sides. But in \n" ); document.write( "a square, all the sides are equal in length. Let's call that length \"a\". This makes \n" ); document.write( "the perimeter equation become: \n" ); document.write( ". \n" ); document.write( "P = a + a + a + a \n" ); document.write( ". \n" ); document.write( "and the four terms on the right side add up to 4a. \n" ); document.write( ". \n" ); document.write( "Therefore, for a square we can say \n" ); document.write( ". \n" ); document.write( "P = 4a \n" ); document.write( ". \n" ); document.write( "where \"a\" is the length of one of the sides. The problem tells you that the perimeter of \n" ); document.write( "the square is 28 feet. So we can replace P with 28 in the equation to get: \n" ); document.write( ". \n" ); document.write( "28 = 4a \n" ); document.write( ". \n" ); document.write( "Finally, we can solve for \"a\" (which is the length of one side) by dividing both sides of \n" ); document.write( "this equation by 4. This division will make the right side of the equation become just \n" ); document.write( "\"a\" and the left side of this equation will be 28/4 which is 7. So the equation reduces to: \n" ); document.write( ". \n" ); document.write( "7 = a \n" ); document.write( ". \n" ); document.write( "And that is the answer. The length of any side of the square is 7 feet. \n" ); document.write( ". \n" ); document.write( "Now on to the second problem. This problem involves a triangle. And we know that a triangle has \n" ); document.write( "three sides. A triangle can have all sides equal, two sides equal, or no sides equal. In \n" ); document.write( "this problem the sides are described as shortest, medium, and longest. So we have a \n" ); document.write( "triangle with all sides different in length. Since we know that the triangle has 3 sides \n" ); document.write( "and all sides are different we can write the perimeter equation as: \n" ); document.write( ". \n" ); document.write( "P = a + b + c \n" ); document.write( ". \n" ); document.write( "where P is the perimeter and a, b, and c are the different lengths of the 3 sides. \n" ); document.write( ". \n" ); document.write( "Now let's look at the information in the problem about the three sides. Let's call the \n" ); document.write( "shortest side \"a\". Then note that the other sides (b and c) are expressed in terms of \n" ); document.write( "\"a\". The medium side (call it side b) is 3 inches longer than \"a\". So side b is equal to a + 3. \n" ); document.write( "Then we are told that the longest side (side c) is twice as long as the shortest side \"a\". So \n" ); document.write( "we know that c = 2a. \n" ); document.write( ". \n" ); document.write( "Now let's return to the perimeter equation and substitute \"a\" for \"a\", \"a + 3\" for b, and \n" ); document.write( "2a for c. When we do those substitutions the perimeter equation becomes: \n" ); document.write( ". \n" ); document.write( "P = a + a + 3 + 2a \n" ); document.write( ". \n" ); document.write( "If we add up all the terms on the right side that contain the letter \"a\" the equation \n" ); document.write( "becomes: \n" ); document.write( ". \n" ); document.write( "P = 4a + 3 \n" ); document.write( ". \n" ); document.write( "Now, recall that the problem told us that P was 23 inches. So, let's substitute 23 inches \n" ); document.write( "for P and get: \n" ); document.write( ". \n" ); document.write( "23 = 4a + 3 \n" ); document.write( ". \n" ); document.write( "We need to get rid of the +3 on the right side. Do this by subtracting 3 from both sides \n" ); document.write( "and this makes the equation become: \n" ); document.write( ". \n" ); document.write( "20 = 4a \n" ); document.write( ". \n" ); document.write( "Solve for \"a\" (the shortest side) by dividing both sides by 4 and you have: \n" ); document.write( ". \n" ); document.write( "5 = a \n" ); document.write( ". \n" ); document.write( "So \"a\" is 5 inches. The medium side is 3 inches longer than the short side. So the medium \n" ); document.write( "side is 5 + 3 = 8 inches. And the longest side is twice the length of the shortest side. \n" ); document.write( "So the longest side is 2 times 5 which equals 10 inches. \n" ); document.write( ". \n" ); document.write( "In summary the three sides are 5, 8, and 10 inches. \n" ); document.write( ". \n" ); document.write( "To check, add these three sides together and you should have the perimeter. Sure enough ... \n" ); document.write( "5 + 8 + 10 does equal 23 inches, just as the problem said it should. \n" ); document.write( ". \n" ); document.write( "Hope this helps you to understand the problems and how to solve them. Don't panic about \n" ); document.write( "this stuff ... stay cool and go back to the basics. You don't even have to say what equation \n" ); document.write( "should I use ... just use what you already know and try to think your way through the \n" ); document.write( "problem. That's what math is all about. Eventually, it will get to be second nature to you \n" ); document.write( "... once you get a lot of practice in. Good luck and keep plugging away at it. \n" ); document.write( ".\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " |