+0  
 
0
26
2
avatar

This is an old coin in ancient China. There is a square hole in the middle and the length of it is 1 unit ( BC = 1). And AB is 2 unit long. Q: what is the area of the coin?

 

 May 19, 2020
 #1
avatar+1498 
+2

The center square has a total area of 1*1 = 1, and the circle has an area of (3/2)^2 * π = 2.25π.

 

So the answer's 2.25π - 1 or ~around 6.07

 

If you dont understand anything feel free to ask!

 May 19, 2020
 #2
avatar+30028 
+2

As follows:

 

 

Edit:  The third line in my derivation should say AD2 not AO2.  The numbers are correct though.

 May 19, 2020
edited by Alan  May 19, 2020

10 Online Users

avatar