Geometry

Parallel and Perpendicular Lines flashcards

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What are parallel lines?Lines and Transversals
Distinct coplanar lines that never intersect.
What are perpendicular lines?Lines and Transversals
Lines intersecting at right angles.
Can two distinct coplanar lines both intersect and be parallel?Lines and Transversals
No.
What is the measure of an angle formed by perpendicular lines?Lines and Transversals
90°.
Do nonperpendicular intersecting lines make a right angle?Lines and Transversals
No.
What is a transversal?Lines and Transversals
A line intersecting two or more coplanar lines at distinct points.
Where are interior angles?Lines and Transversals
Between the two crossed lines.
Where are exterior angles?Lines and Transversals
Outside the two crossed lines.
How many intersections are needed to compare angles along a transversal?Lines and Transversals
At least two.
Can a transversal cross nonparallel lines?Lines and Transversals
Yes.
Corresponding angles occupy what positions?Lines and Transversals
Matching positions at the two intersections.
Where are alternate interior angles?Lines and Transversals
Between the lines, on opposite sides of the transversal.
Where are alternate exterior angles?Lines and Transversals
Outside the lines, on opposite sides of the transversal.
Are same-side interior angles alternate?Lines and Transversals
No; they lie on the same side.
Do angle position names alone prove lines are parallel?Lines and Transversals
No.
Parallel lines make corresponding angles what?Angle Relationships with Parallel Lines
Congruent.
If a corresponding angle is 72°, the other is?Angle Relationships with Parallel Lines
72°.
What condition supports corresponding-angle congruence?Angle Relationships with Parallel Lines
The crossed lines are parallel.
Do corresponding angles sum to 180° generally?Angle Relationships with Parallel Lines
No; they are equal when lines are parallel.
What theorem finds matching-corner measures?Angle Relationships with Parallel Lines
Corresponding Angles Theorem.
Parallel lines make alternate interior angles what?Angle Relationships with Parallel Lines
Congruent.
Parallel lines make alternate exterior angles what?Angle Relationships with Parallel Lines
Congruent.
Alternate angles lie on which sides of transversal?Angle Relationships with Parallel Lines
Opposite sides.
Are alternate exterior angles between the lines?Angle Relationships with Parallel Lines
No.
An alternate interior angle is 60°. Its partner?Angle Relationships with Parallel Lines
60°.
Same-side interior angles total?Angle Relationships with Parallel Lines
180° when the crossed lines are parallel.
Are same-side interior angles congruent in general?Angle Relationships with Parallel Lines
No.
Partner to 110° same-side interior angle?Angle Relationships with Parallel Lines
70°.
What does supplementary mean?Angle Relationships with Parallel Lines
Angle measures sum to 180°.
Where are same-side interior angles?Angle Relationships with Parallel Lines
Between the lines on the same side of transversal.
Corresponding Angles Converse says?Proving Lines Parallel
Equal corresponding angles imply parallel lines.
Does one drawing that looks parallel prove it?Proving Lines Parallel
No.
What must a transversal do for the converse?Proving Lines Parallel
Cut the two coplanar lines at distinct points.
Are corresponding positions at separate intersections?Proving Lines Parallel
Yes.
What conclusion follows from congruent corresponding angles?Proving Lines Parallel
The crossed lines are parallel.
Alternate Interior Angles Converse says?Proving Lines Parallel
Congruent alternate interior angles imply parallel lines.
Alternate Exterior Angles Converse says?Proving Lines Parallel
Congruent alternate exterior angles imply parallel lines.
What conclusion can equal alternate angles justify?Proving Lines Parallel
Parallel lines.
Do alternate angles lie on the same side?Proving Lines Parallel
No.
Can the converse test use equal interior angles on opposite sides?Proving Lines Parallel
Yes.
Same-Side Interior Converse says?Proving Lines Parallel
Supplementary same-side interior angles imply parallel lines.
What sum is required by the converse?Proving Lines Parallel
180°.
Are same-side interior angles inside the pair?Proving Lines Parallel
Yes.
Can 80° and 100° same-side interiors prove parallel?Proving Lines Parallel
Yes; they total 180°.
Can 80° and 90° same-side interiors prove parallel?Proving Lines Parallel
No; they total 170°.
Slope formula?Slopes of Lines
(y₂−y₁)/(x₂−x₁), when the denominator is nonzero.
What is rise?Slopes of Lines
Change in y.
What is run?Slopes of Lines
Change in x.
Why is vertical slope undefined?Slopes of Lines
Its horizontal change is zero.
Does reversing both point orders change slope?Slopes of Lines
No.
Slope of horizontal line?Slopes of Lines
0.
Slope of vertical line?Slopes of Lines
Undefined.
Line rising left to right has what slope?Slopes of Lines
Positive.
Line falling left to right has what slope?Slopes of Lines
Negative.
Does undefined slope mean zero slope?Slopes of Lines
No.
Slopes of distinct nonvertical parallel lines?Slopes of Lines
Equal.
Slopes of nonvertical perpendicular lines?Slopes of Lines
Negative reciprocals.
Product of perpendicular nonzero slopes?Slopes of Lines
−1.
What line is perpendicular to horizontal?Slopes of Lines
Vertical.
Can equal slopes alone show two equations are distinct parallel lines?Slopes of Lines
No. Equal slopes show the lines are parallel or the same line; also check that they are not the same line (different y-intercepts).
What does m mean in y=mx+b?Equations of Parallel and Perpendicular Lines
Slope.
What does b mean in y=mx+b?Equations of Parallel and Perpendicular Lines
Y-intercept.
Slope of y=4x+2?Equations of Parallel and Perpendicular Lines
4.
Y-intercept of y=4x+2?Equations of Parallel and Perpendicular Lines
2.
Two distinct parallel lines in y=mx+b share what?Equations of Parallel and Perpendicular Lines
The same m and different b.
Point-slope form?Equations of Parallel and Perpendicular Lines
y−y₁=m(x−x₁).
What information does point-slope form need?Equations of Parallel and Perpendicular Lines
A slope and a point on the line.
Slope in y−3=2(x−1)?Equations of Parallel and Perpendicular Lines
2.
Point in y−3=2(x−1)?Equations of Parallel and Perpendicular Lines
(1,3).
Can point-slope form be rearranged to y=mx+b?Equations of Parallel and Perpendicular Lines
Yes.
Slope of a line parallel to y=3x+1?Equations of Parallel and Perpendicular Lines
3.
Slope of a line perpendicular to y=3x+1?Equations of Parallel and Perpendicular Lines
−1/3.
What equation is a vertical line through x=4?Equations of Parallel and Perpendicular Lines
x=4.
What equation is a horizontal line through y=5?Equations of Parallel and Perpendicular Lines
y=5.
Must a parallel line through an external point have the same intercept?Equations of Parallel and Perpendicular Lines
No; it has the same slope.