The shaded region is what’s left of the 60° sector after you subtract the area of an equilateral
triangle. To find the area of the shaded region, find the areas of the sector and triangle; then
subtract the latter from the former. The sector is exactly one-sixth of the circle (because 60° is one-
sixth of 360°). Thus,
Use the formula for the area of an equilateral triangle to close in on the answer.
The shaded area, then, is . The answer is (A).
Now that you’ve reviewed all the relevant plane geometry facts and formulas, seen some of the test
makers’ favorite plane geometry situations, and learned a few good Kaplan strategies, it’s time to
put yourself to the test again. If you were disappointed in your performance on the Plane Geometry
Diagnostic Test, here’s your chance to make up for it.
THINGS TO REMEMBER:
Five Facts about Triangles
1. Interior angles add up to 180°.
2. Exterior angle equals sum of remote interior angles.
3. Exterior angles add up to 360°.
4.Each side is greater than the difference between and less than the sum of the other
two sides.