Unit 8 Quiz 2 Flashcards
(20 cards)
Two chords are congruent only if
- Their corresponding arcs are equal so if line AB = line CD arc AB = arc CD and vice versa
- Equidistant from the center
If a diameter or radius is ______ to a chord then it _____ the ___ and its __
Perpendicular
Bisects
Chord
Arc
Inscribed angle / arc relationship
The measure of the inscribed angle is = to half the measure of its intercepted arc
Ex. Inscribed angle AB measure =20
Than the arc measure = 40
What happens when an inscribed angle intercepts a diameter
It is a right angle
If two inscribed angles intercept the same arc ….
The angles are equal
If a quadrilateral is inscribed in a circle then its opposite angles are ___
Supplementary
(Add to 180)
A line is a tangent to a circle if and only if it is _______ to a _______ drawn to the point of tangency
Perpendicular
Radius
If two segments from the same external point are tangent to a circle than they are _____
Congruent
If a polygon is circumscribed around a circle then all sides are _____
Tangent
Justification for chords being equal to arcs and vice versa
If Line AB = line CD than measure of arc AB = measure of arc CD
OR
If measure of arc AB = measure of arc CD than line AB = line CD
Inscribed angle to arc justification
Angle ABC = 1/2 Arc AC
Inscribed angles of quadrilaterals justification
Angle DAB + Angle BCD =180
Opp angles of inscribed quad are supplementary
Intercepting a diameter in inscribed angles justification
Inscribed angles that intercept a diameter are right angles
Overlapping arcs in inscribed angles justification
inscribed angles that intercept the same arc are equal
Tangent external point justification
Tangent segments from same external point are equal
Interior intersections rule
If two secants or chords intersect inside a circle then the measure of the angle formed is equal to half the sum of the measures of the intercepted arc
1/2 (arc AD + arc BC) for angle 1
1/2 (arc AB + arc DC) for angle 2
SEE PAGE 29
On the circle intersections rule
If a secant and a tangent intersect at the point of tangency, then the measure of each angle formed is equal to half the measure of its intercepted arc
1/2 arc AB = angle 1
1/2 arc ACB = angle 2
SEE PAGE 30
Exterior Circle intersections rules:
Two secants:
Secant and Tangent:
Two tangents:
- 1/2 (arc CE - arc BD)
- 1/2 (arc BD - arc BC)
- 1/2 (arc BDC- arc BC)
If secants and/or tangents intersect on the exterior of a circle, then the measure of the angle formed is equal to half the difference of the intercepted arcs
SEE PAGE 30
Segment lengths rules
Intersecting chords/secants inside circle:
Intersecting secants outside the circle:
Intersecting secant and tangent outside the circle:
- The products of one of the lines = the products of the other
A x B = C x D - A (a+b) = C (c+d)
- A squared = B (b+c)
Special rule for two tangents hitting circle
If there are 2 tangents the angle formed by the 2 tangents and its nearest arc = 180