Exploring Circles 9.1
Warm Up Write the equation of each item. 1. FG 2. EH 3. 2(25 –x) = x + 2 4. 3x + 8 = 4x
A circle is the set of all points in a plane that are a given distance from a specific point on that plane. That specific point is called the center. (You name a circle by it’s center) Radius: a segment with one endpoint at the center and the other endpoint ON the circle. Diameter: a segment with endpoints on the circle that passes through the center of the circle. (Diameter = 2 times the radius)
Chord: a segment with endpoints on the circle. Diameter is the largest possible chord. Secant: a line that intersects a circle in exactly two points. It is an extension of a chord. Tangent: a line that intersects a circle in exactly one point.
Identify each segment
Area and Circumference Area of a circle is the number of square units contained within the circle. A = π r ^2 Circumference is the distance around a circle. C = 2 π r or C = π d Do not use 3.14 for pi, us the π button on your calculator.
Name the center of Circle M. Name a chord that is also a diameter. If MD = 5 inches, find RI. Is MI a chord of circle O? Is MI = MA? Name 4 radii of circle M. Is RI > SU? If RI = 11.8 cm, find MA. Draw in segment AB. What kind of triangle is triangle MAR?
Radius Diameter Circumference Area 5 cm 7 cm 136.9 in2 21.24 cm
Find the circumference and area.
Find the circumference and area.