Objectives Angle Pair Relationships Adjacent Angles Vertical Angles Linear Pair Complementary Angles Supplementary Angles
Adjacent angles are “side by side” and share a common ray. 15º 45º
These are examples of adjacent angles. 45º 80º 35º 55º 130º 50º 85º 20º
These angles are NOT adjacent. 100º 50º 35º 35º 55º 45º
When 2 lines intersect, they make vertical angles. 75º 105º 105º 75º
Vertical angles are opposite one another. 75º 105º 105º 75º
Vertical angles are opposite one another. 75º 105º 105º 75º
Vertical angles are congruent 150º 30º 150º 30º
Supplementary angles add up to 180º. 40º 120º 60º 140º Adjacent and Supplementary Angles Supplementary Angles but not Adjacent
Complementary angles add up to 90º. 30º 40º 50º 60º Adjacent and Complementary Angles Complementary Angles but not Adjacent
Linear Pair Two adjacent angles (common vertex and a common ray) that form a straight line. So the two angles add up to ? 180
Practice Time!
Directions: Identify each pair of angles as vertical, supplementary, complementary, linear pair or none of the above.
#1 120º 60º Supplementary Angles And a Linear Pair
#2 60º 30º Complementary Angles
#3 Vertical Angles 75º 75º
#4 60º 40º None of the above
#5 60º 60º Vertical Angles
Supplementary Angles and a Linear Pair #6 135º 45º Supplementary Angles and a Linear Pair
#7 25º 65º Complementary Angles
#8 90º 50º None of the above
Directions: Determine the missing angle.
#1 ? 45º
#1 135º 45º
#2 65º
#2 25º 65º
#3 35º
#3 35º 35º
#4 ? 50º
#4 130º 50º
#5 ? 140º
#5 140º 140º
#6 Rectangle ? 40º
#6 Rectangle 50º 40º
Find angle measures in a linear pair EXAMPLE Find angle measures in a linear pair Two angles form a linear pair. The measure of one angle is 5 times the measure of the other. Find the measure of each angle. ALGEBRA SOLUTION Let x° be the measure of one angle. The measure of the other angle is 5x°. Then use the fact that the angles of a linear pair are supplementary to write an equation.
The measures of the angles are 30° and 5(30)° = 150°. EXAMPLE Find angle measures in a linear pair x + 5x = 180° Write an equation. 6x = 180° Combine like terms. x = 30° Divide each side by 6. The measures of the angles are 30° and 5(30)° = 150°. ANSWER
Find m< AEB 4x +8 6x - 42
Write an equation & Solve
Find the measure of each <
Write an equation & Solve
Homework Page 38 # 3 – 42 (x3) and 49 – 52 all Honors also: # 45, 55, & 56