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Warm Up Find the complement of each angle measure. 1. 30° 2. 42°. 60°. 48°. Find the supplement of each angle measure. 4. 82°. 98°. 3. 150°. 30°. W. Y. Line YZ intersects line WX . YZ intersects WX. X. Z. B. Line AB is parallel to line ML .
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Warm Up Find the complement of each angle measure. 1. 30° 2. 42° 60° 48° Find the supplement of each angle measure. 4. 82° 98° 3. 150° 30°
W Y Line YZ intersects line WX. YZ intersects WX. X Z B Line AB is parallel to line ML. ABML. A L M Reading Math The red arrows on the lines show that the lines are parallel. Intersecting lines are lines that cross at one common point. Parallel lines are lines in the same plane that never intersect.
R Line RS is perpendicular to line TU. RSTU. T U S Line AB and line ML are skew. AB and ML are skew. A M B L Perpendicular lines intersect to form 90° angles, or right angles. Skew lines are lines that lie in different planes. They are neither parallel nor intersecting.
UV and YV UV YV 8-3 Example 1A: Identifying Parallel, Perpendicular, and Skew Lines Tell whether the lines appear parallel, perpendicular, or skew. The lines appear to intersect to form right angles.
XU and WZ XU and WZ are skew. Example 1B: Identifying Parallel, Perpendicular, and Skew Lines Tell whether the lines appear parallel, perpendicular, or skew. The lines are in different planes and do not intersect.
XY and WZ XY || WZ Example 1C: Identifying Parallel, Perpendicular, and Skew Lines Tell whether the lines appear parallel, perpendicular, or skew. The lines are in the same plane and do not intersect.
WX and XU WX XU Check It Out: Example 1A Tell whether the lines appear parallel, perpendicular, or skew. The lines appear to intersect to form right angles.
WX and UV WX and UV are skew. Check It Out: Example 1B Tell whether the lines appear parallel, perpendicular, or skew. The lines are in different planes and do not intersect.
WX and ZY WX || ZY Check It Out: Example 1C Tell whether the lines appear parallel, perpendicular, or skew. The lines are in the same plane and do not intersect.
Vertical angles are the opposite angles formed by two intersecting lines. Angles 1 and 3 in the diagram are vertical angles. Vertical angles have the same measure, so they are congruent. Adjacent angles have a common vertex and a common side, but no common interior points. Angles 2 and 3 in the diagram are adjacent. Adjacent angles formed by two intersecting lines are supplementary
Reading Math Angles with the same number of tick marks are congruent. The tick marks are placed in the arcs drawn inside the angles.
A transversalis a line that intersects two or more lines. Transversals to parallel lines form special angle pairs.
Example 2A: Using Angle Relationships to Find Angle Measures Line n line p. Find the measure of the angle. 2 2 and the 130° angle are vertical angles. Since vertical angles are congruent, m2 = 130°.
Example 2B: Using Angle Relationships to Find Angle Measures Line n line p. Find the measure of the angle. 3 Adjacent angles formed by two intersecting lines are supplementary. m3 + 130° = 180° –130° –130° Subtract 130° to isolate m3. m3 = 50°
Example 2C: Using Angle Relationships to Find Angle Measures Line n line p. Find the measure of the angle. 4 Alternate interior angles are congruent. m4 = 130°.
Check It Out: Example 2A Line n line p. Find the measure of the angle. 45° 4 5 6 2 3 135° 7 n p 3 3 and the 45° angle are vertical angles. Since vertical angles are congruent, m3 = 45°.
Check It Out: Example 2B Line n line p. Find the measure of the angle. 45° 4 5 6 2 3 135° 7 n p 6 6 and the 135° angle are vertical angles. m6 = 135°.
Check It Out: Example 2C Line n line p. Find the measure of the angle. 45° 4 5 6 2 3 135° 7 4 n p Adjacent angles formed by two intersecting lines are supplementary. m4 + 45° = 180° Subtract 45° to isolate m4. –45° –45° m4 = 135°
Lesson Quiz Tell whether the lines appear parallel, perpendicular, or skew. 1.AB and CD 2.EF and FH 3.AB and CG 4. parallel perpendicular skew In Exercise 28, line r || line s. Find the measures of 4, 5, and 7. 55°, 125°, 125°