AMC10 2012 A

AMC10 2012 A · Q4

AMC10 2012 A · Q4. It mainly tests Angle chasing.

Let $\angle ABC = 24^\circ$ and $\angle ABD = 20^\circ$. What is the smallest possible degree measure for $\angle CBD$?

设$\angle ABC = 24^\circ$且$\angle ABD = 20^\circ$。$\angle CBD$的最小可能度数是多少？

(A) 0 0

(B) 2 2

(D) 6 6

(E) 12 12

Answer

Correct choice: (C)

正确答案：（C）

Solution

Ray AB is common to both angles, so the degree measure of $\angle CBD$ is either $24 + 20 = 44$ or $24 - 20 = 4$. The smallest possible degree measure is 4.

射线AB是两个角的公共部分，因此$\angle CBD$的度数或者是$24 + 20 = 44$，或者是$24 - 20 = 4$。最小可能的度数是4。

Topics

GE.001 Angle chasing