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GeronL
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« on: March 21, 2011, 10:23:07 PM » |
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find perimeter of rhombus whose diagonals are 18,12
driving me nuts and google did not help
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안녕하십니까
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Miss Mia
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« Reply #1 on: March 21, 2011, 10:36:19 PM » |
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Here's an example question I found: Yahoo! AnswersQ. Find perimeter of rhombus with diagonals 10 and 24? A. The triangle created by a quarter of the intersection is a right triangle with sides 5 and 12. Using pythagorean theorem to find the remaining side (which is any single edge of the rhombus) gives us sqrt(5^2+12^2)=sqrt(169)=13. Multiplying by 4 to get perimeter gives 52 So for your problem the sides would be 9 & 6. Use Pythagorean theorem c^2 = a^2+b^2 c^2 = 9^2 + 6^2 c^2 = 81 + 36 c^2 = 117 c = 10.816 That's for one side. You need to multiply 10.816 x 4 to get a perimeter of 43.2666 |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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GeronL
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« Reply #2 on: March 21, 2011, 10:38:52 PM » |
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Thanks for the answers, but I still don't understand any of it. :-\
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안녕하십니까
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GeronL
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« Reply #3 on: March 21, 2011, 10:44:01 PM » |
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 Same kind of question is next. I should just give up. diagonals are 14 and 8 what is ^, anyways? lol So that would be 7 and 4. 49 and 16? 65 okay, what was that next step? That is probably what I am totally missing.
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« Last Edit: March 21, 2011, 10:46:21 PM by GeronL »
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안녕하십니까
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Miss Mia
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« Reply #4 on: March 21, 2011, 10:47:38 PM » |
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Thanks for the answers, but I still don't understand any of it. :-\
Maybe this diagram will help:  Okay, so diagonals are the line from A to C and the line D to B. Both create a right (angle) triangle in the center. So you gave the length of the two lines, but the WHOLE line. You use Pythagorean when you have a right triangle and you know two of the three sides. So if you divide the numbers given in half, you automatically have the two inner lines of the triangle. For instance using the diagram, let's just deal with the C to D outside line and the triangle that makes. You know the lengths of the two other lines by dividing 18 and 12 in half, so they're 9 and 6 respectively. So you need to know ONLY the outside line and it's a right triangle so you can use Pythagorean which is a^2 + b^2 = c^2. You're solving for c. c^2 = a^2+b^2 c^2 = 9^2 + 6^2 c^2 = 81 + 36 c^2 = 117 c = 10.816 Now on the second to last line, I don't know how to write square root in computer talk, but to get 10.816 you're just taking the square of 117. All sides of a rhombus are equal. You just multiple the length of one side by 4 to get the perimeter of the whole shape. Does that make more sense? |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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GeronL
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« Reply #5 on: March 21, 2011, 10:48:59 PM » |
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OKAY.
I got it.
Somehow.
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안녕하십니까
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Miss Mia
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« Reply #6 on: March 21, 2011, 10:49:58 PM » |
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Same kind of question is next. I should just give up. diagonals are 14 and 8 what is ^, anyways? lol So that would be 7 and 4. 49 and 16? 65 okay, what was that next step? That is probably what I am totally missing. The ^ means square in computer. So 2^2 is 2*2 = 4 |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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Miss Mia
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« Reply #7 on: March 21, 2011, 10:52:09 PM » |
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OKAY.
I got it.
Somehow.
I think it helps if you can visualize that you're just breaking the rhombus into 4 triangles. |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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Miss Mia
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« Reply #8 on: March 21, 2011, 10:56:57 PM » |
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Are you helping someone with homework or is this your own torturous project? I'm pretty okay with the math, I just have to refresh my memory a bit with geometry. I like algebra, so bring it on if you need more assistance.  |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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GeronL
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« Reply #9 on: March 21, 2011, 10:57:18 PM » |
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lol.
The next question is about the area... I knew this yesterday... I guess my brain is full and learning the perimeter has pushed it out. haha
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안녕하십니까
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GeronL
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« Reply #10 on: March 21, 2011, 10:58:23 PM » |
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Are you helping someone with homework or is this your own torturous project?
Trying to help my niece. Not that I'm much else. |
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안녕하십니까
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Miss Mia
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« Reply #11 on: March 21, 2011, 11:00:01 PM » |
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lol.
The next question is about the area... I knew this yesterday... I guess my brain is full and learning the perimeter has pushed it out. haha
Of a rhombus? Does it give you the diagonals? This is the formula if you have the diagonals:  d1 is the length of a diagonal d2 is the length of the other diagonal |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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Miss Mia
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« Reply #12 on: March 21, 2011, 11:01:18 PM » |
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Trying to help my niece. Not that I'm much else.
What grade is your niece in? |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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GeronL
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« Reply #13 on: March 21, 2011, 11:21:24 PM » |
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10th  She is in the top 2% nationally or something. She is also in AVID, whatever that is |
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안녕하십니까
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Miss Mia
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« Reply #14 on: March 21, 2011, 11:29:54 PM » |
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10th She is in the top 2% nationally or something. She is also in AVID, whatever that is They didn't have AVID at my high school (at least when I was there), I just took some AP courses. |
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"I have the nerve to walk my own way, however hard, in my search for reality, rather than climb upon the rattling wagon of wishful illusions." - Zora Neale Hurston
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