Module · Geometry
Chapter 22: Circles
Geometry
4 topics
What this chapter covers
The 4 topics below make up Circles on the GRE. Click any topic to open its notes, examples and practice test.
Study material & tests
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📝 Chapter test
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Formula Reference Sheet
This chapter
Circle basics
| Diameter | d = 2r |
|---|---|
| Circumference | C = 2πr = πd |
| Area | A = πr² |
Arcs & sectors (θ = central angle)
| Arc length | (θ / 360) × 2πr |
|---|---|
| Sector area | (θ / 360) × πr² |
Angles in a circle
| Central angle | = measure of the arc it cuts off |
|---|---|
| Inscribed angle | = ½ × its intercepted arc (½ of the central angle on the same arc) |
| Angle in a semicircle | = 90° (diameter subtends a right angle) |
GRE reference
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