標題:
area question
發問:
In the figure, ABCD is a rectangle formed by four squares each of area 1 cm^2. DB is a diagonal. Find the area of the shaded region. ans: 7/8 cm^2 how can i get it? plz step by step thanks a lot! 更新: http://upload.lsforum.net/users/public/t34231RWf180.bmp
最佳解答:
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set up a equation... A 是 shaded area 左邊的線... (BC x CD / 2) - ( 3 x A / 2) = (A + 1) x 1 / 2 4x1/2 - 3A/2 = (A+1)/2 (4-3A)/2 = (A+1)/2 4-3A = A+1 4-1 = A+3A 3 = 4A A = 3/4 By substituting A=3/4 into (A+1)x1/2 (3/4 + 1)/2 = 3/8 + 4/8 = 7/8 cm^2
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