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Geometry Using Paper Folding. Lesson 1.4. Definition. Perpendicular lines When two lines intersect at a right angle. B. AC. BD. C. A. D. Definition. Parallel lines Two lines in the same plane that never intersect. AC. BD. A. C. B. D. Definition. Conjecture
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Geometry Using Paper Folding Lesson 1.4
Definition • Perpendicular lines When two lines intersect at a right angle B AC BD C A D
Definition • Parallel lines Two lines in the same plane that never intersect. AC BD A C B D
Definition • Conjecture A statement that you think is true. An “educated guess” based on observation.
Activity 1Perpendicular and Parallel Lines • What kind of lines are l and n? Perpendicular • What kind of lines are mandn? Parallel
Conjecture • Complete the following conjecture about parallel and perpendicular lines: If two coplanar lines are perpendicular to the same line, then the lines are parallel.
Definition Distance from a point to a line: the length of the perpendicular segment from the point to the line.
Definition • Segment bisector A line that divides a segment into two congruent parts. B E C A D
Definition • Midpoint The point in the middle of a segment. Divides the segment into two congruent parts. MIDPOINT C B A
Definition • Perpendicular bisector a segment bisector that is perpendicular to the segment B C A E D
Definition • Angle bisector a segment that bisects an angle. B D A C