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September 29th, 2012, 04:22 AM  #1 
Member Joined: Sep 2012 From: Norway Posts: 35 Thanks: 0  I have a question about the area of this shape?
Picture 1 and 3 are related to this question; Where did the nr. 15 come from? Picture 3: How do I figure this out? I found the area of the circle and then I found the area of the other shape and lastly added the two. (Of course, I was wrong.) 
September 29th, 2012, 04:26 AM  #2  
Member Joined: Sep 2012 From: Norway Posts: 35 Thanks: 0  Re: I have a question about the area of this shape? Quote:
 
September 29th, 2012, 05:04 AM  #3 
Global Moderator Joined: Dec 2006 Posts: 18,586 Thanks: 1489 
The triangle is being assumed to be equilateral, so that half its base is 15 cm. That's how the value "15" was obtained. Picture 3 seems to be giving an unrelated shape. I suggest you find the shape's area by adding the area of its rectangular lower portion to the area of its semicircular upper portion. Are you able to do that? 
September 29th, 2012, 05:33 AM  #4  
Member Joined: Sep 2012 From: Norway Posts: 35 Thanks: 0  Re: Quote:
 
September 29th, 2012, 05:40 AM  #5 
Global Moderator Joined: Dec 2006 Posts: 18,586 Thanks: 1489 
If you post your working, we can check it for you.

September 29th, 2012, 06:10 AM  #6  
Member Joined: Sep 2012 From: Norway Posts: 35 Thanks: 0  Re: Quote:
Half circle: 0.0314*0.76 = 0.023 0.39 + 0.023 = 0.413 m^2 The answer is supposed to be 0.62 m^2  
September 29th, 2012, 06:34 AM  #7 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,155 Thanks: 464 Math Focus: Calculus/ODEs  Re: I have a question about the area of this shape?
For the area of the semicircle, you want to take half the diameter, then square it and multiply by ?/2: Recall the area of a circle is Then the total area is about: 

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