Difference between revisions of "1983 AHSME Problems/Problem 4"

(Solution)
Line 24: Line 24:
 
F = (1, 1.732);
 
F = (1, 1.732);
 
draw(A--B--C--D--E--F--A);
 
draw(A--B--C--D--E--F--A);
label("A", A, A);
+
label("$A$", A, NW);
label("B", (0.3, 0.866));
+
label("$B$", B, 3W);
label("C", (-0.1, 0));
+
label("$C$", C, SW);
label("D", D, D);
+
label("$D$", D, SE);
label("E", E, E);
+
label("$E$", E, E);
label("F", F, F);
+
label("$F$", F, NE);
 
draw(B--D, dashed+linewidth(0.5));
 
draw(B--D, dashed+linewidth(0.5));
 
draw(B--E, dashed+linewidth(0.5));
 
draw(B--E, dashed+linewidth(0.5));

Revision as of 09:10, 2 September 2017

Problem 4

Position $A,B,C,D,E,F$ such that $AF$ and $CD$ are parallel, as are sides $AB$ and $EF$, and sides $BC$ and $ED$. Each side has length of $1$ and it is given that $\measuredangle FAB = \measuredangle BCD = 60^\circ$. The area of the figure is

$\text{(A)} \ \frac{\sqrt 3}{2} \qquad  \text{(B)} \ 1 \qquad  \text{(C)} \ \frac{3}{2} \qquad  \text{(D)}\ \sqrt{3}\qquad \text{(E)}$

Solution

Solution

[asy] pair A, B, C, D, E, F; A = (0, 1.732); B = (0.5, 0.866); C = (0,0); D = (1, 0); E = (1.5, 0.866); F = (1, 1.732); draw(A--B--C--D--E--F--A); label("$A$", A, NW); label("$B$", B, 3W); label("$C$", C, SW); label("$D$", D, SE); label("$E$", E, E); label("$F$", F, NE); draw(B--D, dashed+linewidth(0.5)); draw(B--E, dashed+linewidth(0.5)); draw(B--F, dashed+linewidth(0.5)); [/asy]

Drawing the diagram as described, we create a convex hexagon with all side lengths equal to 1. In this case, it is a natural approach to divide the figure up into four equilateral triangles. The area, A, of one such equilateral triangle is $\frac{\sqrt{3}}{4}$, which gives a total of $4\left(\frac{\sqrt{3}}{4}\right) = \sqrt{3}$, or $\boxed{D}$.

See Also

1983 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 3
Followed by
Problem 5
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 26 27 28 29 30
All AHSME Problems and Solutions


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