Circle Basics
This is the distance from the center of a circle to any point on the circle.
What is the radius?
An arc smaller than 180° is called this.
What is a minor arc?
A line that touches a circle at exactly one point.
What is a tangent?
The formula to find diameter when you know the radius.
What is d = 2r?
The set of all points in a plane that are the same distance from a fixed point.
What is a circle?
This line segment passes through the center and touches two points on the circle.
What is the diameter?
An arc greater than 180° is called this.
What is a major arc?
A line that intersects a circle in exactly two points.
What is a secant?
The formula for radius when given the circumference.
What is r = C / (2π)?
The fixed point from which every point on a circle is equidistant.
What is the center?
This is the formula used to find the circumference of a circle.
This is the formula used to find the circumference of a circle.
What is C = 2πr or C = πd?
This is an angle whose vertex is at the center of a circle.
What is a central angle?
The point where a tangent touches a circle.
What is the point of tangency?
The area of a semicircle with radius r.
What is A = (1/2)πr²?
A part of the circle’s edge defined by two endpoints.
What is an arc?
This formula finds the space inside a circle.
What is A = πr²?
This type of angle has its vertex on the circle and its sides are chords.
What is an inscribed angle?
A radius drawn to the point of tangency is always this to the tangent line.
What is perpendicular?
The circumference of a circle with diameter 10.
What is C = π × 10 = 10π?
The part of a secant line that lies inside the circle.
What is a chord?
This is exactly half of a circle.
What is a semicircle?
The measure of an inscribed angle is always this fraction of the intercepted arc.
What is half?
If two tangents are drawn from the same external point, they are always this.
What is congruent?
The radius of a circle with area 25π.
What is r = 5?
The region bounded by an arc and two radii.
What is a sector?