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The Encyclopedia of Geometry (0225)
Problem If perpendicular lines $BE$ and $DF$ are drawn from $B$ and $D$ to any line $XY$ that passes through the vertex $C$ of square $ABCD$, then $$DF+BE=EF \qquad or \qquad |DF-BE|=EF.$$ $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$…
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Hioki Shrine (1911), Shinshu-shinmachi, Nagano City, Nagano Prefecture (10)
Problem Five people, $A, \ B, \ C, D$ and $E$, decided to invest a total of $1,560 \ yen$. $B$ invested $30 \ yen$ less than $A$, $C$ invested $50 \ yen$ less than $B$, $D$ invested $80 \ yen$ less than $C$, and $E$ invested $110 \ yen$ less than $D$. Find the…
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The Encyclopedia of Geometry (0224)
Problem If the feet of the perpendiculars drawn from the opposite vertices $A$ and $C$ of the square $ABCD$ to any line passing through the other vertex ($B$ or $D$) are $A’$ and $C’$, respectively, then $$AA’=BC’.$$ $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$…
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Hioki Shrine (1911), Shinshu-shinmachi, Nagano City, Nagano Prefecture (09)
Problem There is an isosceles trapezoid with an upper base of $6 \ ft$, a lower base of $12 \ ft$, and a height of $8 \ ft$. Divide this into two isosceles trapezoids of the same area by a line parallel to the bottom base. Then, find the lengths of $EF$ and $GH$. $$…
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The Encyclopedia of Geometry (0223)
Problem If we take an arbitrary $G$ on the side $DC$ of a square $ABCD$ and draw the square $GCEF$ outside the $ABCD$ with one side being $CG$, then $$DE⊥BG \qquad and \qquad DE=BG.$$ $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$…
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The Encyclopedia of Geometry (0222)
Problem If we take the point $E$ on the diagonal $BD$ of a square $ABCD$ so that $AB=BE$, and the perpendicular line passing through that point intersects $CD$ at the point $F$, then $$CF=ED.$$ $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$…
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Hioki Shrine (1911), Shinshu-shinmachi, Nagano City, Nagano Prefecture (08)
Problem You decide to buy chestnut, paulownia, and mulberry seedlings for $1,500 \ yen$. The price of a paulownia seedling is $80$ % of that of a chestnut seedling, and the price of a mulberry seedling is half that of a paulownia. Then, how much do the chestnut, paulownia, and mulberry seedlings cost? $$ $$…
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The Encyclopedia of Geometry (0221)
Problem If $F$ is the point at which the perpendicular line $CE$ drawn from the vertex $C$ of a rectangle $ABCD$ to the diagonal $BD$ intersects with the bisector of the angle $∠A$, then $$AC=CF.$$ $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$…
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The Encyclopedia of Geometry (0220)
Problem If the quadrilateral formed by the intersection of the bisectors of each vertex angle of a quadrilateral is a square, what should the original quadrilateral be like? $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ Solution Let $PQRS$ be…
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The Encyclopedia of Geometry (0219)
Problem The diagonal of a rectangle is longer than any line segment drawn between its opposite sides. $$ $$ $$ $$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $\downarrow$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ $$ Solution Let $EF$ be any line segment drawn between $AB$ and $CD$. If we draw…