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x + 4 x = 90; 18, 72. ANSWER. 2. Find m ABD . What kind of angle is it?. 180° , straight. ANSWER. 1. The sum of two numbers is 90 and one number is 4 times the other. Write an equation and solve to find the numbers.
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x + 4x = 90; 18, 72 ANSWER 2. FindmABD. What kind of angle is it? 180° , straight ANSWER 1. The sum of two numbers is 90 and one number is 4 times the other. Write an equation and solve to find the numbers.
In the figure, name a pair of complementary angles, a pair of supplementary angles, and a pair of adjacent angles. Because 32°+ 58° = 90°, BACand RSTare complementary angles. Because 122° + 58° = 180°,CADand RSTare supplementary angles. Because BACand CADshare a common vertex and side, theyare adjacent. EXAMPLE 1 Identify complements and supplements SOLUTION
In the figure, name a pair of complementary angles, a pair of supplementary angles, and a pair of adjacent angles. 1. ANSWER FGK and GKL, HGKandGKL, FGKandHGK for Example 1 GUIDED PRACTICE
Are KGHand LKGadjacent angles ? Are FGKand FGHadjacent angles? Explain. 2. ANSWER No, they do not share a common vertex. No, they have common interior points. for Example 1 GUIDED PRACTICE
Given that 1 is a complement of 2 and m1 = 68°, • find m2. a.You can draw a diagram with complementary adjacent angles to illustrate the relationship. m 2 = 90° – m 1 = 90° – 68° = 22° EXAMPLE 2 Find measures of a complement and a supplement SOLUTION
m 3 = 180° – m 4 = 180° –56° = 124° b. Given that 3 is a supplement of 4and m 4=56°, find m3. b.You can draw a diagram with supplementary adjacent angles to illustrate the relationship. EXAMPLE 2 Find measures of a complement and a supplement SOLUTION
When viewed from the side, the frame of a ball-return net forms a pair of supplementary angles with the ground. Find mBCEand mECD. EXAMPLE 3 Find angle measures Sports
Use the fact that the sum of the measures of supplementary angles is 180°. STEP1 mBCE+m∠ ECD=180° EXAMPLE 3 Find angle measures SOLUTION Write equation. (4x + 8)°+ (x +2)°=180° Substitute. 5x + 10 = 180 Combine like terms. 5x = 170 Subtract10 from each side. x = 34 Divide each side by 5.
STEP2 Evaluate: the original expressions when x = 34. m ECD = (x + 2)° = ( 34 + 2)° = 36° m BCE = (4x + 8)° = (4 34 + 8)° = 144° ANSWER The angle measures are144°and36°. EXAMPLE 3 Find angle measures SOLUTION
3. Given that 1 is a complement of 2 and m2 = 8o, find m1. ANSWER ANSWER 82o 63o 4. Given that 3 is a supplement of 4 and m3 = 117o, find m4. 5. LMNand PQRare complementary angles. Find the measures of the angles if m LMN= (4x –2)o and m PQR = (9x + 1)o. ANSWER 26o, 64o for Examples 2 and 3 GUIDED PRACTICE
Identify all of the linear pairs and all of the vertical angles in the figure at the right. ANSWER 1 and 5 are vertical angles. 1 and 4 are a linear pair. 4 and 5 are also a linear pair. ANSWER EXAMPLE 4 Identify angle pairs SOLUTION To find vertical angles, look or angles formed by intersecting lines. To find linear pairs, look for adjacent angles whose noncommon sides are opposite rays.
ALGEBRA 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. 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. EXAMPLE 5 Find angle measures in a linear pair SOLUTION
The measures of the angles are 30oand 5(30)o = 150o. ANSWER EXAMPLE 5 Find angle measures in a linear pair xo+ 5xo = 180o Write an equation. 6x = 180 Combine like terms. x = 30o Divide each side by 6.
6. Do any of the numbered angles in the diagram below form a linear pair? Which angles are vertical angles? Explain. ANSWER No, no adjacent angles have their noncommon sides as opposite rays, 1 and 4 , 2 and 5,3 and 6, these pairs of angles have sides that from two pairs of opposite rays. For Examples 4 and 5 GUIDED PRACTICE
60°, 30° ANSWER For Examples 4 and 5 GUIDED PRACTICE 7. The measure of an angle is twice the measure of its complement. Find the measure of each angle.
o 1. 1 and 2 are supplementary. If m 1 = 97 , findm 2. o ANSWER 83 o 2. 3 and 4 are complementary angles. If m 3= 74,Findm 4. o ANSWER 16 Daily Homework Quiz
o 96 ANSWER 3. FindmEFH. 4. FindmABC. o 36 ANSWER Daily Homework Quiz
ANSWER No; once you have drawn a pair of vertical angles, you have drawn two pairs of opposite rays. This automatically gives another pair of vertical angles. Daily Homework Quiz 5.Is it possible to draw a figure that contains exactly one pair of vertical angles? Explain.