Difference between revisions of "2005 AMC 10A Problems/Problem 12"
m (added category) |
(→Video Solution) |
||
(7 intermediate revisions by 6 users not shown) | |||
Line 9: | Line 9: | ||
The area of the ''trefoil'' is equal to the area of a small equilateral triangle plus the area of four <math>60^\circ</math> sectors with a radius of <math>\frac{2}{2}=1</math> minus the area of a small equilateral triangle. | The area of the ''trefoil'' is equal to the area of a small equilateral triangle plus the area of four <math>60^\circ</math> sectors with a radius of <math>\frac{2}{2}=1</math> minus the area of a small equilateral triangle. | ||
− | This is | + | This is equivalent to the area of four <math>60^\circ</math> sectors with a radius of <math>1</math>. |
So the answer is: | So the answer is: | ||
Line 15: | Line 15: | ||
<math>4\cdot\frac{60}{360}\cdot\pi\cdot1^2 = \frac{4}{6}\cdot\pi = \frac{2}{3}\pi \Rightarrow B </math> | <math>4\cdot\frac{60}{360}\cdot\pi\cdot1^2 = \frac{4}{6}\cdot\pi = \frac{2}{3}\pi \Rightarrow B </math> | ||
− | ==See | + | ==See also== |
− | + | {{AMC10 box|year=2005|ab=A|num-b=11|num-a=13}} | |
− | + | {{MAA Notice}} | |
− | |||
− | |||
− | |||
− |
Revision as of 12:57, 25 November 2020
Problem
The figure shown is called a trefoil and is constructed by drawing circular sectors about the sides of the congruent equilateral triangles. What is the area of a trefoil whose horizontal base has length ?
Solution
The area of the trefoil is equal to the area of a small equilateral triangle plus the area of four sectors with a radius of minus the area of a small equilateral triangle.
This is equivalent to the area of four sectors with a radius of .
So the answer is:
See also
2005 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by Problem 11 |
Followed by Problem 13 | |
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 AMC 10 Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.