2002 masterpiece problem
The mensuration of a concave quadrangle.
Otani junior high school (in Osaka)
| [Problem] Ask for the area of a right quadrangle. |  |
| Solution 1 If the right angle 2 equilateral triangle of 12cm of equilateral is written as shown in a figure, a light-blue form will become congruent. 12x12/2=72 (cm2) Answer 72cm2
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| Solution 2 The sum of height will be set to 12cm if it divides into two triangles of 12cm of bases as shown in a figure. 12x12/2=72 (cm2) Answer@72cm2 |
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| Solution 3 The reverse side obtains and carries out a light-blue portion, and the whole will become a trapezoid symmetrical with a line if 12cm neighborhoods are piled up. Especially, 12cm of diagonal lines intersects perpendicularly. 12x12/2=72 (cm2) Answer@72cm2 |
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