Circle Flashcards
Practice (25 cards)
What is the definition of a circle?
A circle is a set of points in a plane that are equidistant from a fixed point called the center.
What is the formula for the circumference of a circle?
The circumference of a circle is given by the formula C = 2πr, where r is the radius.
What does ‘π’ (pi) approximately equal?
π (pi) is approximately equal to 3.14159.
What is the formula for the area of a circle?
The area of a circle is given by the formula A = πr², where r is the radius.
What is the diameter of a circle?
The diameter of a circle is twice the radius and is the longest distance across the circle.
What is the relationship between diameter and radius?
The diameter is equal to twice the radius (d = 2r).
True or False: The radius is half the diameter.
True.
What is the chord of a circle?
A chord is a line segment whose endpoints lie on the circle.
What is a tangent to a circle?
A tangent is a line that touches the circle at exactly one point.
What is a secant line?
A secant line is a line that intersects the circle at two points.
What is the center of a circle?
The center of a circle is the fixed point from which all points on the circle are equidistant.
What is the formula for the length of an arc in a circle?
The length of an arc is given by the formula L = (θ/360) × C, where θ is the central angle in degrees.
What is a sector of a circle?
A sector is a region enclosed by two radii and the arc between them.
What is the formula for the area of a sector?
The area of a sector is given by the formula A = (θ/360) × πr², where θ is the central angle in degrees.
What is the formula for finding the radius if you know the circumference?
The radius can be found using the formula r = C/(2π), where C is the circumference.
What is the formula for finding the radius if you know the area?
The radius can be found using the formula r = √(A/π), where A is the area.
What is the total angle sum around a point in a circle?
The total angle sum around a point in a circle is 360 degrees.
What is the relationship between a circle’s radius and its circumference?
The circumference is directly proportional to the radius, as given by C = 2πr.
What is the equation of a circle in Cartesian coordinates?
The equation of a circle with center (h, k) and radius r is (x - h)² + (y - k)² = r².
What is the term for the distance from the center of the circle to any point on the circle?
The term is called the radius.
What is a diameter in relation to a circle?
The diameter is the longest chord of the circle and passes through the center.
What is the term for the distance around a circle?
The term is called the circumference.
True or False: The area of a circle increases with the square of the radius.
True.
What is the formula to calculate the diameter from the area?
The diameter can be calculated using the formula d = 2√(A/π), where A is the area.
