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January 26th, 2013, 10:57 AM  #1 
Member Joined: Jan 2013 Posts: 47 Thanks: 0  Final question of the day !. Circles !
Last question I am stuck on.Many thanks to everyone who helped me today. Question is attached 
January 26th, 2013, 10:58 AM  #2 
Member Joined: Jan 2013 Posts: 47 Thanks: 0  Re: Final question of the day !. Circles !
Note if that attachment does not work this one should

January 26th, 2013, 11:26 AM  #3 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Final question of the day !. Circles !
In your attachment, none of the area is shaded.

January 26th, 2013, 11:29 AM  #4 
Member Joined: Jan 2013 Posts: 47 Thanks: 0  Re: Final question of the day !. Circles !
Good Point! Right Here is attachment with it shaded 
January 26th, 2013, 11:53 AM  #5 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Final question of the day !. Circles !
Have you identified what it is you need to know in order answer this question?

January 26th, 2013, 12:01 PM  #6 
Member Joined: Jan 2013 Posts: 47 Thanks: 0  Re: Final question of the day !. Circles !
Yes , The area formula for circles pi R squared Which was, 4pi for each You would then need to work out the area of the semicircle then subtract area of 2 circles from semicircle, But how would you work out the area of the semicircle ? 
January 26th, 2013, 06:02 PM  #7 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Final question of the day !. Circles !
What I meant was, we need to know the diameter (or radius) of the semicircle. Hint: Consider the right half of the diagram only. Now, draw a radius of the semicircle through the center of the smaller circle. Use the Pythagorean theorem to determine the radius of the semicircle. What do you find? 
January 26th, 2013, 11:17 PM  #8 
Member Joined: Jan 2013 Posts: 47 Thanks: 0  Re: Final question of the day !. Circles !
Not much ! I presume the radius of the semicircle is the hypotenuse but how would I find out the lengths of the other 2 sides ??? 
January 26th, 2013, 11:34 PM  #9 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Final question of the day !. Circles !
Consider the diagram: [attachment=0:1b13qg7k]circleswithinsemicircle.jpg[/attachment:1b13qg7k] So, what must the radius of the semicircle be? 
January 27th, 2013, 01:56 AM  #10  
Global Moderator Joined: Dec 2006 Posts: 20,753 Thanks: 2136  Quote:
 

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