F.2 maths - Ans.fyi 參考答案

F.2 maths

v人仔v

2006-10-30 11:51 pm

click個網,有幅圖http://www.flypicture.com/bin/?id=qNryk67e

1.In the figure, CDE is a straight line. If a+b=360˙ and a+c=180˙, prove that
a)AB//CD,
b)BC//DF.

2.Use the digits 0,0,1,2,3 to form a number which must be correct to 5 significant figures. 請解釋
A 0.0123
B 0.1230
C 1.0230
D 12 300

3.http://www.flypicture.com/bin/?id=qNryk6jY 請詳列每個步驟

thx

更新1:

3)0.5aX2/3%=5/3% 0.5a=5/3%÷2/3% 0.5a=5/3X3/2 a=2.5÷0.5 a=5 sorry!我唔明點會變左0.5aX2/3% 條式:http://img68.imageshack.us/img68/8011/009uv6.gif

回答 (1)

pui yuet

2006-11-01 3:20 am

✔ 最佳答案

1.
a)∵∠BCD+b=360°
∴∠BCD=360°-b
a+b=360°(given)
a=360°-b
∴∠BCD=a
∵∠BCD=∠ABC
∴AB//CD(alt. ∠s equal)

b))∵∠CDF+c=180°
∴∠CDF=180°-c
a+c=180°(given)
a=180°-c
∴∠CDF=c
∵∠BCD=∠CDF
∴BC//DF(alt. ∠s equal)

2.Ans is C
0.0123=>3 sig. fig.
0.1230=>4 sig. fig.
12300=>可能只有3個

3.(為免混淆，我用a代替x)
0.5aX2/3%=5/3%
0.5a=5/3%÷2/3%
0.5a=5/3X3/2
a=2.5÷0.5
a=5

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