2015 AMC 8 Problems/Problem 2
Contents
Problem
Point is the center of the regular octagon
, and
is the midpoint of the side
What fraction of the area of the octagon is shaded?
Solutions
Solution 1
Since octagon is a regular octagon, it is split into
equal parts, such as triangles
, etc. These parts, since they are all equal, are
of the octagon each. The shaded region consists of
of these equal parts plus half of another, so the fraction of the octagon that is shaded is
Solution 2
The octagon has been divided up into identical triangles (and thus they each have equal area). Since the shaded region occupies
out of the
total triangles, the answer is
. -Flare
Solution 3
For starters what I find helpful is to divide the whole octagon up into triangles as shown here:
Now it is just a matter of counting the larger triangles remember that and
are not full triangles and are only half for these purposes. We count it up and we get a total of
of the shape shaded. We then simplify it to get our answer of
.
Video Solution
~savannahsolver
See Also
2015 AMC 8 (Problems • Answer Key • Resources) | ||
Preceded by Problem 1 |
Followed by Problem 3 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
All AJHSME/AMC 8 Problems and Solutions |
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