Circle Vocabulary C Circle set of all pointsequidistant
Circle Vocabulary
C Circle – set of all pointsequidistant _____ from a given point called the center _____ of the circle. Symbol: C
CHORD: A segment whose endpoints are on the circle
DIAMETER: P Distance across the circle through its center Also known as the longest chord.
RADIUS: P Distance from the center to point on circle
Formula Radius = ½ diameter or Diameter = 2 r
Use P to determine whether each statement is true or false. Q R P T S
Secant Line: intersects the circle at exactly TWO points
Tangent Line: a LINE that intersects the circle exactly ONE time Forms a 90°angle with one radius Point of Tangency: The point where the tangent intersects the circle
Name the term that best describes the notation. t n a Sec s u i Rad Diame t e r Ch or d t n e g n a T
Important Vocab Note! When describing and discussing these landmarks related to the circle use two letters like we used with polygons.
Central Angles An angle whose vertex is at the center of the circle
3 Types of Arcs A Major Arc Minor Arc More than 180° Less than 180° P ACB To name: use 3 letters C AB B To name: use 2 letters APB is a Central Angle
Semicircle: An Arc that equals 180° D E To name: use 3 letters P F EDF
THINGS TO KNOW AND REMEMBER ALWAYS A circle has 360 degrees A semicircle has 180 degrees Vertical Angles are CONGRUENT Linear Pairs are SUPPLEMENTARY
Formula measure Arc = measure Central Angle
Find the measures. EB is a diameter. m AB = 96° A E m ACB = 264° Q m AE = 84° 96 B C
Arc Addition Postulate A C B m ABC = m AB + m BC
Tell me the measure of the following arcs. AC is a diameter. m DAB =240 m BCA = 260 D C 140 R 40 100 80 B A
Congruent Arcs have the same measure and MUST come from the same circle or of congruent circles. C B A 45 45 D 110 Arc length is proportional to “r”
Textbook p. 396 #11 p. 404 #11 – 16, 25 – 30, 38
- Slides: 22