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Adjacent, Linear Pairs Vertical, Supplementary, and Complementary Angles
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Objectives-What we’ll learn…
Identify and use adjacent angles and linear pairs of angles. Identify and use vertical, complementary and supplementary angles.
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Adjacent angles are “side by side” and share a common ray.
15º 45º
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These are examples of adjacent angles.
45º 80º 35º 55º 130º 50º 85º 20º
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These angles are NOT adjacent.
100º 50º 35º 35º 55º 45º
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Linear pair of angles two angles that share a vertex form a straight line (add to 180°)
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B D 130 A 50 E AEB & BED are a linear pair of angles. They form a straight line & =180.
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When 2 lines intersect, they make vertical angles.
75º 105º 105º 75º
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Vertical angles are opposite to one another.
75º 105º 105º 75º
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Vertical angles are opposite one another.
75º 105º 105º 75º
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Vertical angles are congruent (equal).
150º 30º 150º 30º
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Supplementary angles add up to 180º.
40º 120º 60º 140º Adjacent and Supplementary Angles Supplementary Angles but not Adjacent
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Complementary angles add up to 90º.
30º 40º 50º 60º Adjacent and Complementary Angles Complementary Angles but not Adjacent
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Practice Time!
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Directions: Identify each pair of angles as vertical, supplementary, complementary, or none of the above.
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#1 120º 60º
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#1 120º 60º Supplementary Angles
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#2 60º 30º
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#2 60º 30º Complementary Angles
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#3 75º 75º
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#3 Vertical Angles 75º 75º
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#4 60º 40º
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#4 60º 40º None of the above
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#5 60º 60º
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#5 60º 60º Vertical Angles
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#6 135º 45º
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#6 135º 45º Supplementary Angles
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#7 25º 65º
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#7 25º 65º Complementary Angles
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#8 90º 50º
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#8 90º 50º None of the above
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Directions: Determine the missing angle.
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#1 ?º 45º
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#1 135º 45º
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#2 ?º 65º
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#2 25º 65º
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#3 ?º 35º
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#3 35º 35º
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#4 ?º 50º
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#4 130º 50º
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#5 ?º 140º
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#5 140º 140º
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#6 ?º 40º
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#6 50º 40º
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Applications of Complementary and Supplementary Angles
Let x = the measure of an angle, then = complement of the angle, and = supplement of the angle Now let us apply this information.
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x = 18 (measure of the complement) 4x = 72 (measure of the angle)
Example #1 The measure of an angle is 4 times the measure of its complement. Find the measure of the angle and the measure of its complement. Solution (Method #1) Let x = the measure of the complement. Let 4x = the measure of the angle x + 4x = 90 5x = 90 x = 18 (measure of the complement) 4x = 72 (measure of the angle)
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Example #1 Method #2 Let x = the measure of the angle
Let 90 – x – measure of the complement x = 4(90 – x) x = x 5x = 360 x = 72 (angle measure) 90 – x = 18 (complement measure)
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Example #2 The ratio of the complement of an angle to the supplement of the angle is 2:7. Find the measure of the original angle. Solution: Let x = the angle measure Let 90 – x = measure of the complement Let 180 – x = measure of the supplement
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Example #2 (Continued)
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