2017年10月10日SAT官方每日一题---数学选择.

　　为了让我们更好的适应sat考试，sat官网每天都会有sat官方每日一题，下面是小编为您整理的2015年10月sat官方每日一题，是数学选择，让我们一起来看一看这道数学选择吧。

　　Read the following SAT test question and then click on a button to select your answer.

　　In the figure above, the circle with center A and the circle with center C are tangent at point D. If the circles each have radius 10, and if line l is tangent to the circle with center A at point B, what is the value of x?

　　(A) 55

　　(B) 60

　　(C) 63

　　(D) 65

　　(E) It cannot be determined from the information given.

　　答案：B

　　解析：

　　The circles each have radius 10, so A B = A D = D C = 10. Since the circles are tangent at point D, segment Line AC contains D and A C = 20. Also, line A B and l are perpendicular because a line tangent to a circle forms a right angle with the radius at the point of tangency. Therore, triangle A B C is a right triangle with hypotenuse 20 and side line A B of length 10. A right triangle with one side of length one-half that of its hypotenuse is a 30 degree - 60 degree - 90 degree triangle. The 30 degree angle is opposite side line A B, so x = 90 minus 30 = 60.

　　为了让我们更好的适应sat考试，sat官网每天都会有sat官方每日一题，上面是小编为您整理的2015年10月sat官方每日一题，是数学选择，让我们一起来看一看这道数学选择吧。