<PRE><B>Question 698535</B>
&lt;br&gt;&lt;font face=&quot;Tahoma&quot;&gt;A rhombus is a parallelogram with 4 equal sides.&lt;br&gt;

So if you know the length of one side, you know the length of all 4 sides.&lt;br&gt;

Also, the diagonals of a rhombus always bisect each other,&lt;br&gt;

and they are always perpendicular to each other.&lt;br&gt;

So let&#39;s draw the diagonals, where M is the intersection of the diagonals,&lt;br&gt;

and notice we will form a right triangle AMD.&lt;br&gt;

Using this, we can find DM, and we know that {{{DM=(1/2)*DB}}}&lt;br&gt;

We can use the Pythagorean Theorem at this point.&lt;br&gt;

{{{(AM)^2+(DM)^2=(AD)^2}}}&lt;br&gt;

{{{5^2+(DM)^2=12^2}}}&lt;br&gt;

{{{25+(DM)^2=144}}}&lt;br&gt;

{{{(DM)^2=119}}}&lt;br&gt;

{{{DM=sqrt(119)}}}&lt;br&gt;

Since {{{DM=(1/2)*DB}}}, we can see that:&lt;br&gt;

{{{sqrt(119)=(1/2)*DB}}}&lt;br&gt;

{{{2*sqrt(119)=DB}}}&lt;br&gt;

So diagonal {{{DB=2*sqrt(119)}}} cm or approximately 21.8 cm.&lt;br&gt;

I hope this helps!  Keep practicing!  :)&lt;br&gt;

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