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1992 AMC 12 Question 26

AMC12 · 1992 AMC 12

Question 26

Semicircle $\overset{\frown}{AB}$ has center $C$ and radius $1.$ Point $D$ is on $\overset{\frown}{AB}$ and $CD\perp AB.$ Extend $\overline{BD}$ and $\overline{AD}$ to $E$ and $F,$ respectively, so that circular arcs $\overset{\frown}{AE}$ and $\overset{\frown}{BF}$ have $B$ and $A$ as their respective centers. Circular arc $\overset{\frown}{EF}$ has center $D.$ The area of the shaded “smile,” $AEFBDA,$ is

Question illustration
  1. $(2-\sqrt2)\pi$
  2. $2\pi-\pi\sqrt2-1$
  3. $\left(1-\frac{\sqrt2}{2}\right)\pi$
  4. $\frac{5\pi}{2}-\pi\sqrt2-1$
  5. $(3-2\sqrt2)\pi$