SAT数学备考练习
Read the following SAT test question, then click on a button to select your answer.
In the figure above, x = 60 and y = 40. If the dashed lines bisect the angles with measures of x° and y°, what is the value of z?
A.25
B.35
C.40
D.45
E.50
Correct Answer: E
Here"s Why:
First, add the labeled points A, B, C, D, E, and O to the figure, as shown above. Then segment
bisects
AOC, so m
AOB = m
BOC, and m
AOB + m
BOC = x° = 60°. Thus, m
AOB = m
BOC = 30°. Similarly, m
COD = m
DOE = 20°, because
COD and
DOE are of equal measure and the sum of their measures is y° = 40°. From the figure, it follows that z° = m
