國中求面積

[p26131]

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請問這題該如何解？

[thepiano]

△CDE = (5/6)(1/2)ABCD = (5/12)ABCD

△BCF = (1/2)(1/2)ABCD = (1/4)ABCD

△AEF = (1/6)(1/2)(1/2)ABCD = (1/24)ABCD

△CEF = (1 - 5/12 - 1/4 - 1/24)ABCD = (7/24)ABCD = 63

[p26131]

△CDE = (5/6)(1/2)ABCD = (5/12)ABCD

△BCF = (1/2)(1/2)ABCD = (1/4)ABCD

△AEF = (1/6)(1/2)(1/2)ABCD = (1/24)ABCD

△CEF = (1 - 5/12 - 1/4 - 1/24)ABCD = (7/24)ABCD = 63

請問老師為什麼 △AEF = (1/6)(1/2)(1/2)ABCD 那三個分數是怎麼來的壓?

[thepiano]

AE = (1/6)AD
AF = (1/2)AB
後面的 (1/2) 是因它是三角形