1. 2-8 Proving Angle Relationships You identified and used special pairs of angles. Use the Angle Addition Postulate to find the measure of angles.

2. Page 151 in your book

3. Protractor Postulate Does for angles what the Ruler Postulate does for segments. It guarantees that any angle has exactly one measure. It also ensures that all angles measures are less than 180°.

4. Page 151 in your book Angle addition postulate is like the segment addition postulate. This means we can add two angles together and they will equal the one big angle.

5. Try It M R Q N P 87°

6. Try It A B C D 3X° (4X−3)°

7. CONSTRUCTION Using a protractor, a construction worker measures that the angle a beam makes with a ceiling is 42°. What is the measure of the angle the beam makes with the wall? The ceiling and the wall make a 90  angle. Let  1 be the angle between the beam and the ceiling. Let  2 be the angle between the beam and the wall. m  1 + m  2= 90Angle Addition Postulate 42 + m  2= 90m  1 = 42 42 – 42 + m  2= 90 – 42Subtraction Property of Equality m  2= 48Substitution Answer:The beam makes a 48° angle with the wall.

8. A.32 B.94 C.104 D.116 Find m  1 if m  2 = 58 and m  JKL = 162.

9. Page 152 in your book.

10. A.20 B.30 C.40 D.50 QUILTING The diagram shows one square for a particular quilt pattern. If m  BAC = m  DAE = 20, and  BAE is a right angle, find m  CAD.

11. 2-8 Assignment Page 156, 8-13 Find the measure of each numbered angle only.