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September 30, 2014

September 30, 2014

Posted by **Piggy** on Thursday, February 23, 2012 at 12:58am.

- geometry -
**Reiny**, Thursday, February 23, 2012 at 8:06amArea = 3 equal rectangles + 2 equal equilateral triangles

the rectangels are easy, each is 5 by 10 or 50 cm^2

For the triangle, if you know two sides and the contained angle Ø between those sides, then the area

= (1/2)(side1)(side2)sinØ

we know it is equilateral so the angle is 60°

area of base triangle = (1/2)(5)(5)sin60°

= 25/2 (√3/2) = 25√3/4 cm^2

or

height of triangle:

h^2 + 25/4 = 25

h^2 = 75/4

h = √(75/4) = 5√3/2

area = (1/2)base x height = (1/2)(5)(5√3/2) = 25√3/4

add up the rectangles and triangles.

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