100 likes | 298 Views
Circles. Honors Math – Grade 4. A. Circle. A circle is a plane figure. All the points on a circle are the same distance from a given point, called the center. Point A is the center of the circle. Circle A. A circle is named by its center point. C. E. B. D. G. F.
E N D
Circles Honors Math – Grade 4
A Circle • A circle is a plane figure. • All the points on a circle are the same distance from a given point, called the center. • Point A is the center of the circle Circle A A circle is named by its center point.
C E B D G F The Parts of Circle B • All the line segments in Circle B have special names. • Can you name any points on the circle? • E, C, D, F, G
C E B D G F Radius • A radius is a line segment with endpoints at the centerof the circle and on the circle. • is a radius. • Can you name any other radii (plural of radius)?
C E B D G F Diameter • A diameter is a line segment that passes through the center of the circle and has bothendpoints on the circle. • is a diameter. The length of the diameter is always equal to twice the length of the radius. 12 cm If BE measures 6 cm, how long is CD?
C E B D G F Chord • A chord is a line segment with both endpoints on the circle. • is a chord. • Are there any other chords in Circle B? • Line segment CD A diameter is a special chord.
Simple Closed Curve • A simple closed curve is a path that begins and ends at the same point and does not cross itself. Simple Closed Curves Not simple closed curves
P T V S R X W Q Practice • Name the circle and its center. • How many diameters are shown? Name the diameters. • Is TR a radius? Explain why or why not? • Is VX a radius? Explain why or why not? • How many radii are shown? Name the radii.
Practice Answers • ____________________________________________ • ____________________________________________ • ____________________________________________ • ____________________________________________ • ____________________________________________
Practice Answers • Circle V. The center is point V. • There are 3 diameters. PQ, RS, TW • TS is not a radius because it does not have an endpoint at the center of the circle and it is a chord. • VX is a radius because its endpoints are the center point V and point X on the circle. • There are 7 radii. VP, VS, VW, VQ, VX, VR, VT