8.1 Circle Terminology and Chord Properties This section will
introduce you to some of the most important aspects of circle
geometry Radius Diameter Tangent Chord
Slide 3
Circumference The perimeter of a circle Radius A segment
connecting the center of a circle with a point on the circle
Diameter A segment that goes through the center of the circle and
connects to two points on the outside of the circle Chord A segment
whose end points are on the circle Tangent A line that intersects
the circle on exactly one point
Slide 4
The sum of the interior angles of a triangle is 180 The number
of degrees in a circle is 360 Circumference = d = 2r Area of a
circle = r 2 Pythagorean Theorem states that the sum of the squares
of the legs of a right triangle is equal to the square of its
hypotenuse a 2 + b 2 = c 2 180 360 a c b
Slide 5
Formulas in Action Example 1: Find angle B Solution 1: -ABC is
isoceles, so B = C -A + B + C = 180 -50 + B + B = 180 -2(B) = 130
-B = 65 A BC 50 C B A 12 5
Slide 6
Some Important Chord Properties The Diameter perpendicular to a
chord bisects the chord and its arc If AB CD, then CE = ED The
perpendicular bisector of a chord passes through the center of the
circle If AB CD and AE = EB, then CD passes through the center of
the circle A E B DC A B C D E