Homework Help: Geometry HELP

Posted by Ariel on Saturday, June 12, 2010 at 1:37am.

In a rhombus, one diagonal has a length of 10 cm and the area is 120 cm2. Find the length of one side.
a.)10cm
b.)12cm
c.)13cm

Geometry HELP - drwls, Saturday, June 12, 2010 at 1:58am
A rhombus has equal side lengths. The two intersecting diagonals create four congruent right triangles of area 30 cm^2 each.
Let side length = a

30 = (1/2)*5* sqrt(a^2 -5^2)
12 = sqrt(a^2 -25)
144 = a^2 -25
a^2 = 169
a = 13

The length of the other diagonal is
2*sqrt[(13^2 - 5^2)] = 24 cm

Interesting problem!
Geometry HELP - Ariel, Saturday, June 12, 2010 at 2:15am
This is an interesting problem:) Thanks!!

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