Angles and Parallel Lines
When parallel lines are crossed by another line called a transversal, special angles are formed.
These special angles are:
Videos below can give extra information on the 3 angles.
Alternate Angles:
Corresponding Angles:
Co-interior Angles:
Examples:
![Picture](/uploads/2/3/4/0/23408802/6533666.png?217)
1. Find the value of the variable in this diagram.
Solution
y° = 60°
*alternate angles are equal*
Solution
y° = 60°
*alternate angles are equal*
![Picture](/uploads/2/3/4/0/23408802/6631809.png?215)
2. Find the value of d in the diagram.
Solution
*co-interior angle is formed and equal 180°*
d° = 180 - 95
d° = 85°
Solution
*co-interior angle is formed and equal 180°*
d° = 180 - 95
d° = 85°
![Picture](/uploads/2/3/4/0/23408802/8179612.png)
3. Prove that the lines AB and CD are parallel in the diagram.
Solution
*alternate angles equal*
∠AEF is alternate to ∠DFE
∠AEF = ∠DFE = 40°
∴ AB || CD
Solution
*alternate angles equal*
∠AEF is alternate to ∠DFE
∠AEF = ∠DFE = 40°
∴ AB || CD
Quiz
1. Find the value of each of the variables in the diagrams below and explain your answer.
2. Find the values of the pro numerals.
3. Solve in the diagrams below whether AB is parallel to CD and give reasons.