CHAPTER VII LINES AND ANGLES POSITION OF TWO

CHAPTER VII LINES AND ANGLES

POSITION OF TWO LINES H E F D G segments AB and CD are two parallel lines C AB and BC are two A B intersecting lines AB and EH are two skew segments ( neither parallel nor intersecting)

Definition of an angle A Legs, AB and BC B C Vertex the area of angle components of the angle. Two sides ( legs ). Vertex. The area

TYPES OF ANGLES 1. Right angle : an angle with the measure of 90 2. Acute angle : an angle with the measure is less than 90 3. Straight angle : angle with the measure of 180

4. Obtuse angle : an angle with the measure is greater than 90 but less than 180 5. Reflection angle : an angle with the measure is greater than 180

CONSTRUCTING ANGLES 1. Dividing an angle into two equal part a. Draw an arc using a protractor with O as the centre so that the arc intersects OA at C and OB at D b. Consider, then draw an arc with C as the centre and the radius i similar to step 2. do the same with D. You will get two arc intersects at a point in region AOB. Give P as the name of the point. c. Connect O to P

B D P O A C

THE PROPERTIES OF LINES 1. Straight lines 2. 3. Horizontal lines Vertical lines 4. Parallel lines

5. Intersection lines 6. Superimpose lines 7. Perpendicular lines 8. Skew lines

THE RELATIONSHIP BETWEEN ANGLES AND LINES Alternate interior angles 1 2 5 6 ∠ 2 and ∠ 7 ∠ 4 and ∠ 5 3 4 7 8 Alternate exterior angles ∠ 1 and ∠ 8 ∠ 3 and ∠ 6 Corresponding angles ∠ 1 and ∠ 5 Suplementary interior angles ∠ 3 and ∠ 7 ∠ 4 and ∠ 7 ∠ 2 and ∠ 5 ∠ 2 and ∠ 6 ∠ 4 and ∠ 8 Suplementary exterior