Homework Help: math

Posted by jennie on Tuesday, January 25, 2011 at 11:41pm.

I am a third grader and have a homework of sketching and labeling all possible rectangles with perimeter of 30 cm and sides whose lengths are whole numbers. I am confuse, i need help please.

math - helper, Tuesday, January 25, 2011 at 11:47pm
The formula for perimeter is,
P = 2w + 2 L
30 = 2w + 2L
30 = 2(w + l)
15 = w + l

So, for a perimeter of 30, you want to sketch rectangles that the width and length total 15.

Some possible rectangles,
14 + 1 = 15
13 + 2 = 15
12 + 3 = 15
11 + 4 = 15
10 + 5 = 15
9 + 6 = 15
8 + 7 = 15

Do you follow what I am doing?
I gave you a good start. Find the remaining sides that when added, equal 15.

Good luck! :)
math - jennie, Wednesday, January 26, 2011 at 12:10am
I will try. This will help me to start and gave me an idea. Thank you very much.
math - helper, Wednesday, January 26, 2011 at 12:20am
You're welcome.

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