D
Area and circumference are easy to confuse, and x is the diameter (not the radius) of the original circle. Read carefully to
avoid these subtle traps. And remember: every time you see a circle, find the radius.
Since x is the diameter of the circle, x = 2r = 12. A circle with a radius of 2x would have a radius of 2(12) = 24 and a
circumference of 2 π (24) = 48π.
53.
J
Since opposite angles in a parallelogram are equal, you can find a by finding x + y. What in this problem would allow you to
find x + y? Since x and y are both angles of the central triangle, you can find their sum by using the fact that the interior angles
of a triangle add up to 180°.
Since opposite angles in a parallelogram are equal, a = x + y, so a = 105. Note that solving for the actual degree values of
angles x, y, or z would be unnecessary and impossible.
54.
E
Train yourself to recognize Pythagorean triplets, such as 3:4:5 and 5:12:13, and their multiples—doing so will not only
provide insights that often lead to answers, but also save you valuable time otherwise spent on needless calculation.
55.
