Lines Section 5.1 Essential question: How are the measures of angles related when parallel lines are cut by a transversal? https://www.brainpop.com/math/geometryandmeasuremen t/parallelandperpendicularlines/
Vocabulary When two lines intersect in a plane and form right angles they are called __________________________. Two lines are called _________________ when they are in the same plane and do not intersect.
Graphic Organizer Parallel Lines Perpendicular Lines Symbols Define it in your own words Draw it Describe a real-world example of it
Key Concept: Transversals and Angles A line that intersects two or more lines is called a _______________, and eight angles are formed ______________ lie inside the lines. Examples: ___________________ ______________ lie outside the lines.
Key Concept: Transversals and Angles __________________ are interior angles that lie on opposite sides of the transversal. When the lines are parallel, their measures are equal. Examples: ________________ __________________ are exterior angles that lie on opposite sides of the transversal. When the lines are parallel, their measures are equal. Examples: ____________________
Key Concept: Transversals and Angles ___________________ are those angles that are in the same position on the two lines in relation to the transversal. When the lines are parallel, their measures are equal. Examples: ______________________
Examples Classify each pair of angles in the figure as alternate interior, alternate exterior, or corresponding. 1. ∠4 and ∠8 2. ∠1 and ∠7 3. ∠2 and ∠6
Notes: Find Missing Angle Measures When two parallel lines are cut by a transversal, special angle relationships exist. If you know the measure of one of the angles, you can find the measures of all of the angles. Suppose you know that the measure of angle 1 is equal to 50 degrees. You can use that to find the measures of angles 2, 3, and 4. m ∠ 2 = Because ______________________________ m ∠ 3 = m ∠ 4 = Because _______________________________
Examples If m∠4 = 122°, find each given angle measure. Justify your answer. 1. m∠8 2. m∠5 3. m∠2 4. m∠1
Essential Question How are the measures of the angles related when parallel lines are cut by a transversal? ______________________________________________________________________________