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by **teddybear101** on Wed Feb 24, 2010 10:06 pm

if given a rhombus ABCD. the perimeter of ABCD is 80 cm, CD=2x+6. find x. can i have help findinga place where i can learn this type of information. also help with this problem? :confused:

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by **little_dragon** on Wed Feb 24, 2010 10:08 pm

look up the def of a "rhombus"
what does it say abt the sides?
use this to find x
4(2x+6)=80
:wave:

by **teddybear101** on Wed Feb 24, 2010 10:10 pm

ok, well i have tryed to solve and ended up with answer 7. is this correct ? :confused:

by **Armando** on Fri Sep 17, 2010 10:19 pm

You have a rhombus ABCD. AB+BC+CD+DA = 80. CD = 2x+6.

Since all sides of a rhombus are equal, you can set up the equation:

$4(2x+6)=80$

Distribute:

$8x + 24 = 80$

Subtract 24

$8x = 80 - 24$

Divide by eight:

$x = \frac {80-24}{8}$

Simplify:

$x = \frac{56}{8}$
$x = 7$

Let's check it by plugging it into the original equation.

$4(2*7+6)=80$
$4(14+6) = 80$
$4(20) = 80$
$80 = 80$

7 is correct.

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