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May 19th, 2008, 04:11 PM
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| | geometry help I need help solving these math problems, I have no idea how to do them: 
the circle one I need the are aof the shaded figure
the p-gram one, i need the area
the pentagon, I need the apothem, area, and side length | 
May 19th, 2008, 04:23 PM
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| | The area of the shaded regions in the circle.
The sides of the triangle with hypoteneuse 6 inches are the same, They are the radius of the circle:
The subtended angle is 90 degrees.
Area of circular segment:
That's one of them. Multiply by 2.
For the rhombus, find the area of one of the right triangles and multiply by 4. | | The following users thank galactus for this useful post: | |  | 
May 19th, 2008, 04:25 PM
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| | Quote:
Originally Posted by Zyger I need help solving these math problems, I have no idea how to do them: 
the circle one I need the are aof the shaded figure
the p-gram one, i need the area
the pentagon, I need the apothem, area, and side length | For the circle problem, you need to compute the radius first, which is  . Then, the area of the semicircle is  . We subtract out the area of the triangle to obtain the area of the shaded region:  .
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May 19th, 2008, 06:00 PM
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| | may please have some more help on the others? | 
May 19th, 2008, 06:05 PM
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Originally Posted by Zyger I need help solving these math problems, I have no idea how to do them: 
the circle one I need the are aof the shaded figure
the p-gram one, i need the area
the pentagon, I need the apothem, area, and side length | A useful formula to know is that
For a regular n-gon of sidelength b | 
May 19th, 2008, 06:08 PM
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| | Quote:
Originally Posted by Zyger I need help solving these math problems, I have no idea how to do them: 
the circle one I need the are aof the shaded figure
the p-gram one, i need the area
the pentagon, I need the apothem, area, and side length |
All I need now is the one with the pentagon | 
May 19th, 2008, 06:19 PM
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Originally Posted by Zyger All I need now is the one with the pentagon | A general desire for the underyling is never hurtful
usign my formula
So now apply it
plug in your b value
and use the fact that
to find the apothem | 
May 19th, 2008, 06:31 PM
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Originally Posted by Mathstud28 A general desire for the underyling is never hurtful
usign my formula
So now apply it
plug in your b value
and use the fact that
to find the apothem | I am so sorry, but that math looks like a foreign language to me. Can you go a little slower with it please? | 
May 19th, 2008, 06:41 PM
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Originally Posted by Zyger I am so sorry, but that math looks like a foreign language to me. Can you go a little slower with it please? | Of course this is a site to learn
Ok so basically we have that
where a is apothem and p is permieter
Now since we know that the exterior angle of a n-gon is  we know due to the linear pair postulate that the interior angle of an n-gon is
so for a pentagon(5-gon)
the interior angle would be
So now we know that the angle at a vertex is 108 we know that the apothem bisects it making
the angle that the apothem cuts off 44...so now we have a right triangle with angles ,90,44,46
So we need to calculate the apothem or in this case we are given it but we need to find sidelenght
so we use trig
and since that gives us half of our side we see that the sidelenghts are
21.75
now we go to our formula
Now since  where n is the sidelength we see that
so now we see | | The following users thank Mathstud28 for this useful post: | |  | 
May 19th, 2008, 06:42 PM
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| | SORRY POR MY POST, i HAVE TO EDIT NOW | 
May 19th, 2008, 06:49 PM
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Originally Posted by Mathstud28 Of course this is a site to learn
Ok so basically we have that
where a is apothem and p is permieter
Now since we know that the exterior angle of a n-gon is  we know due to the linear pair postulate that the interior angle of an n-gon is
so for a pentagon(5-gon)
the interior angle would be
So now we know that the angle at a vertex is 108 we know that the apothem bisects it making
the angle that the apothem cuts off 44...so now we have a right triangle with angles ,90,44,46
So we need to calculate the apothem or in this case we are given it but we need to find sidelenght
so we use trig
and since that gives us half of our side we see that the sidelenghts are
21.75
now we go to our formula
Now since  where n is the sidelength we see that
so now we see  |   
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