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熱賣及精選
引用:
原帖由 好望角234 於 2021-3-23 09:29 PM 發表

12197412
(a)
ΔAFE ~ ΔCFB (AAA)
BC = AD = AE + ED
so AE : BC = AE : AD = 4 : 5
Area of ΔAFE : Area of ΔCFB = 4² : 5² = 16 : 25

(b)
The area of Area of ΔAFE is 16 cm².

By (a), the area of Area of ΔCFB is 16 ÷ 16 × 25 = 25 cm².

By the corresponding sides of similar triangles, AF : FC = AE : BC = 4 : 5
Area of ΔABF : Area of ΔFBC = 4 : 5
          (because they share the same base AC (and same height))
That is, the area of ΔABF = 25 ÷ 5 × 4 = 20 cm²

Therefore, the area of ΔABC = 20 + 25 = 45 cm²

Thus, the area of the parallelogram ABCD = 2 × 45 = 90 cm².

[ 本帖最後由 top11 於 2021-3-23 10:18 PM 編輯 ]



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