SOLUTION: Mr. Javier designed an arch made of bent iron for the top of a schools main entrance. The 12 segments between the two concentric semicircles are each 0.8 meter long. Suppose

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Question 997069: Mr. Javier designed an arch made of
bent iron for the top of a schools main
entrance. The 12 segments between
the two concentric semicircles are
each 0.8 meter long. Suppose the
diameter of the inner semicircle is 4
meters. What is the total length of the
bent iron used to make this arch?
please help me to solve this problem, thatk you
Answer by KMST(5328)   (Show Source): You can put this solution on YOUR website!
It may look like this:
or maybe the 12 straight segments are placed between the two semicircles
in a different arrangement.
There are straight pieces measuring each, for a total of
.
There are also half-circle arcs.
The inside arc has a radius of .
The outside arc has a radius of .
Since the circumference of a circle of radius can be calculated as ,
the length of a semicircle of radius can be calculated as
.
So, the length needed for the inside semicircle is
,
and the length needed for the outside semicircle is
.
The total length of the bent iron used to make the arch is about
.
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