Question

YN

求解

4.
△ABC中,∠C=90°
tan BAD=
9
AC:BC=3:5,D在BC上,又BD:CD=2:3
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*
.or

數學

Answer 1

綾

如圖
令角BAC = θ
tanθ = 5/3

所求
= tan(θ - 45°)
= (tanθ - tan45°)/(1 + tanθtan45°)
= (5/3 - 1)/(1 + 5/3)
= 1/4