The correct answer is B
Explanation
The circles each have radius 10, so 
. Since the circles are tangent at point D, segment 
contains D and 
. Also, 
and 
are perpendicular because a line tangent to a circle forms a right angle with the radius at the point of tangency. Therefore, 
is a right triangle with hypotenuse 20 and side of length 10. A right triangle with one side of length one-half that of its hypotenuse is a 
triangle. The 
angle is opposite side 
, so 
.
Mathematics > Standard Multiple Choice
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 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.
