Circles Flashcards
Questions about arc length or sector area what do you need to know?
central angle / 360 = arc length / circumference = sector area / total area
Any line in a circle from one edge to another edge is?
A chord
Radius
The line that connects the center point of the circle, out to the edge of the circle
Diameter
A chord that goes through the center of the circle
An angle created by two radii
Central angle
- Can define a piece of the circumference which is called an arc
Sector
Part of the area of a circle
Area of a circle
pi r^2
Circumference of a circle
C = 2 pi r
Circumference formula with diameter?
C = pi d
If in a circle problem you are given an arc section is 1/6 of the circumference then what is the central angle facing that arc?
it would be 1/6th of 360 which = 60
What does inscribed mean?
It means inside and as large as possible
If the diameter of the circle is also a side of an inscribed triangle, then that triangle is a right triangle
What is the radius of a circle with a circumference of 100 ?
50 / pi NOT 50 pi
Margaret needs to determine the radius of her bike tire. If she notes that in one revolution of the tire, the bike travels 64pi centimeters, what is the radius of the tire in centimeters?
Answer = 32.
In one revolution, a wheel travels the distance of its circumference. The circumference of her tire is then 64 pi, so r = 32.
The ratio of the radii of two circles is 1:4, what is the ratio of the circumference of the smaller circle to that of the larger?
Answer = 1/4
