Circles Flashcards
Circumference equation
c = 2πr | c= πd
π to 2 d.p.
3.14
How do you figure out the radius from the diameter?
radius = diameter/2
How do you work out the arc length?
arc length = 2πr x (θ/360)
[where θ is the central angle]
How do you figure out the diameter of a circle, given its circumference?
d = c/π
What is the circumference of a circle?
The distance once around a circle (perimeter).
Area of a circle equation
a = πr²
What is the centre of a circle?
The fixed point from which all points on the boundary of the circle are equidistant (of equal distances).
What is the radius of a circle?
The distance from the centre of a circle to the outside.
What is the diameter of a circle?
The distance across the circle, going through the centre.
What is an arc of a circle?
A part of the circumference of a circle.
Major arc - greater than half the circumference
Minor arc - less than half the circumference
What is the area of a circle?
The space inside the circle.
What is a chord in a circle?
A line segment going from one point of the circumference to another, but doesn’t go through the centre.
What is a secant in a circle?
A line that goes through the circle at two points.
What is a tangent in a circle?
A straight line that touches the circle at a single point only.
