Solve Geometrical Problems with Angles in Parallel Lines

In this activity, we will solve geometrical problems by calculating missing angles in parallel lines.   

 

Let's recap on the three rules. 

 

1  Alternate angles

 

 

Alternate angles form a Z shape. The angles are the same.

 

 

2 Corresponding

 

 

Corresponding angles form an F shape. The angles are the same.

 

 

3 Co-Interior

 

 

Co-interior angles form a C shape.They are not the same, but they add up to 180^o

 

 

Let's use these facts in a question!

 

Example

Find the missing angles and give reasons.

 

 

 

Answer

Angle A forms a Z shape with 58^o

A = 58^o (alternate angles)

 

Angle B forms a C shape with 110^o

B = 180 - 110 = 70^o (co-interior angles)

 

Angle C is an X from 110^o

C = 110^o (vertically opposite)

 

When we get questions like this in an exam, there are as many marks for the reasons as there are for the answer!

 

Let's try some questions!