F4 Maths 313

2011-12-27 7:44 pm

In the figure, AT is tangent to the circle at T and ABC is a straight line. Find AT.

圖片參考：http://imgcld.yimg.com/8/n/HA00149615/o/701112270020813873415610.jpg

回答 (1)

2011-12-27 9:34 pm

✔ 最佳答案

∠ ACT = ∠ BTA (∠in alt. segment)∠ CAT = ∠ CAT (common)△ATB ~ △ACT (AAA)AT/9 = (16 + 9)/ATAT² = 9 * 25AT = 15

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