MathDB
Diagrams and 3D Geo

Source: 2022 AMC10A #21

November 11, 2022
AMCAMC 102022 AMC 10a2022 AMC3D geometryarea

Problem Statement

A bowl is formed by attaching four regular hexagons of side 1 to a square of side 1. The edges of adjacent hexagons coincide, as shown in the figure. What is the area of the octagon obtained by joining the top eight vertices of the four hexagons, situated on the rim of the bowl?
[asy] size(200); defaultpen(linewidth(0.8)); draw((342,-662) -- (600, -727) -- (757,-619) -- (967,-400) -- (1016,-300) -- (912,-116) -- (651,-46) -- (238,-90) -- (82,-204) -- (184, -388) -- (447,-458) -- (859,-410) -- (1016,-300)); draw((82,-204) -- (133,-490) -- (342, -662)); draw((652,-626) -- (600,-727)); draw((447,-458) -- (652,-626) -- (859,-410)); draw((133,-490) -- (184, -388)); draw((967,-400) -- (912,-116)^^(342,-662) -- (496, -545) -- (757,-619)^^(496, -545) -- (446, -262) -- (238, -90)^^(446, -262) -- (651, -46),linewidth(0.6)+linetype("5 5")+gray(0.4)); [/asy]
<spanclass=latexbold>(A)</span>6<spanclass=latexbold>(B)</span>7<spanclass=latexbold>(C)</span>5+22<spanclass=latexbold>(D)</span>8<spanclass=latexbold>(E)</span>9<span class='latex-bold'>(A) </span>6\qquad<span class='latex-bold'>(B) </span>7\qquad<span class='latex-bold'>(C) </span>5+2\sqrt{2}\qquad<span class='latex-bold'>(D) </span>8\qquad<span class='latex-bold'>(E) </span>9