Cao qi2010-02-22 02:10:08 +0000 #1
There is a football is 32 black and white leather sewing made, a black Paper has five angle, a White has six angle, sewing, the White and Black, two corner pieces together in a corner. Football with the equation, there are Black, White of the number of blocks?
To have the process and the column-type
qishi_qishi_2010-02-22 02:14:06 +0000 #2
set as x faster black and white for the y around the block
As the black is white and white surrounded by three black, then from the black side of the same, there are
5x = 3y
also known to get by
x + y = 32
solution of equations have
x = 12
y = 20
crazyzzt2010-02-22 02:51:35 +0000 #3
seemingly The 12 black and white is 32-12 = 20
-based black-x-block, and the white is 32-x, E of edges, V vertices
5x + (32-x) * 6 = E * 2 (each 1 two skin edge shared)
5x + (32-x) * 6 = V * 3 (skin every three to share a vertex)
V +32- E = 2 (Euler formula)
solution was x = 12
So, for the 12 black pentagons, hexagons for the White 20
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