Is there a formula for this??

J

justbreathe

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So the problem is: The perimeter of a rectangle is the same as its height. The height is three more than the base. What are the dimensions of this rectangle?

There are also other variants of this problem such as : The perimeter of a rectangle is 72 cm. The base is three times the height. What are the dimensions of this rectangle?

I'm a 9th grader, in Hon. Geometry for the second time after failing it in 8th grade. I'm great at many aspects of math but for some reason, finding the factors of numbers and what goes with what to make a certain number is just incredibly difficult. So I was wondering if there is a formula(s) for these types of problems that would work to solve them? Even if it's a complex equation with a lot of steps, I can guarantee that it would take me less time to do than sit down, list all the possibilities and try each one, because I just don't have the time to do that.

I'm not just being lazy, really, I just find this incredibly difficult. So if there's anything you can think of at all, pleeeeease let me know.
 
justbreathe said:
So the problem is: The perimeter of a rectangle is the same as its height. The height is three more than the base. What are the dimensions of this rectangle?
Click to expand...
Are you sure about the wording of this statement? Double check it, it doesn't sound right.

As for the second question, you know the perimeter (P) and you can relate the sides of a rectangle to each other. ie. the base is three time the height.

Draw a rectangle labeling the sides x and 3x, (which is which?). The equation then sets up like:

2(x) + 2(3x) = P
 
Ah, typo. *same as the area.
Thank you SO MUCH for the formula for the second one, I have no idea why that didn't occur to me to try.
 
the first one sets up the same way then. You have a similar rectangle to draw. This time you're not given P, but they say it's equal to A, so? What's the formula for the area of a rectangle?
 
justbreathe said:
Then I would just have A = 2x + 3
But, having not been given A, how could i solve that?
Click to expand...

No, that's not the area of a rectangle. What's the general formula for area or a rectangle?
 
Correct, so if the base is x and the height is 3x, then

(3x)(x) = A and you know the equation for P and you also know A = P

there are multiple steps to this problem. It helps to write them all out and draw the rectangles as well, with the proper labeling. If you are having issues with a certain set of problems, there are no short cuts :)
 
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