We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. cookie policy and privacy policy.
 
+0  
 
0
141
1
avatar+107 

The five circles making up this archery target have diameters of length 2, 4, 6, 8, and 10. What is the total red area?

Simplify your answer as much as you can. 

 

[asy] size(4cm);path a=Circle((0,0),5);path b=Circle((0,0),4);path c=Circle((0,0),3);path d=Circle((0,0),2);path e=Circle((0,0),1);fill(a,red); fill(b,white); fill(c,red); fill(d,white); fill(e,red);[/asy]

Since I checked one that was already made of this, none of those answers worked. So please help ASAP!

 Mar 25, 2019
 #1
avatar+102417 
0

Area of innermost red area  =   pi (2/2)^2  =  pi  units^2

 

Area of next red area  =  pi [ (6/2)^2 - (4/2)^2 ]  =  pi [ 3^2 -  2^2 ]  = 5 pi  units^2

 

Area of last red area =  pi [ (10/2)^2 - (8/2)^2 ]  =  pi [ 5^2 - 4^ 2 ]  = 9pi units^2

 

So....the total of the red areas =  

 

pi [ 1 + 5 + 9 ]  =

 

15 pi units^2

 

 

cool cool cool

 Mar 25, 2019

7 Online Users