Circles & Arcs Flashcards
9 cards from real Geometry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 9 Circles & Arcs flashcards as text
What is the center of a circle?
Answer: The point equidistant from all points on the circle
The center of a circle is a unique point from which all points on the circumference are an equal distance. This equidistant property is fundamental to the definition of a circle. Any line segment from the center to the edge is a radius.
What is the radius of a circle?
Answer: The distance from center to edge
The radius of a circle is defined as the distance from its center to any point on its circumference (the edge of the circle). It is a fundamental measurement used in calculating a circle's area and circumference. All radii in the same circle have equal length.
What is a diameter?
Answer: A line through the center connecting two points on the circle
A diameter is a straight line segment that passes through the exact center of a circle and connects two points on its circumference. It represents the longest possible chord in a circle. The diameter is a crucial measurement, as it is twice the length of the radius.
What is the relationship between radius and diameter?
Answer: Diameter is twice the radius
The relationship between the radius (r) and diameter (d) of a circle is straightforward: the diameter is always exactly twice the length of the radius. Conversely, the radius is half the length of the diameter. This can be expressed as d = 2r or r = d/2.
What is a chord in a circle?
Answer: A segment connecting two points on the circle
A chord in a circle is defined as any straight line segment that connects two distinct points on the circle's circumference. It does not necessarily pass through the center. The longest possible chord in a circle is its diameter.
What is an arc?
Answer: A part of the circumference between two points
An arc is a continuous portion of the circumference of a circle. It is essentially a curved segment of the circle's outer edge, defined by two points on the circumference. Arcs are measured in degrees or by their length.
What is a semicircle?
Answer: Half of a circle
A semicircle is precisely half of a circle. It is formed by cutting a circle along its diameter, resulting in an arc that spans 180 degrees. The diameter forms the straight edge of the semicircle.
What is the circumference of a circle?
Answer: The distance around the circle
The circumference of a circle refers to the total distance around its outer edge. It is analogous to the perimeter of a polygon. This measurement is crucial for understanding the size of a circle and is calculated using the radius or diameter.
What is the formula for the circumference of a circle?
Answer: C = 2πr
The formula for the circumference (C) of a circle is C = 2πr, where 'r' is the radius of the circle and 'π' (pi) is a mathematical constant approximately equal to 3.14159. Alternatively, since the diameter (d) is twice the radius, the formula can also be written as C = πd. This formula calculates the distance around the circle.