Teach Genie
Teach it back in your own words, spot gaps, and remember it better.
Parallel lines stay the same distance apart and never meet. We write AB∥CDAB \parallel CDAB∥CD when two lines are parallel.
A transversal is a line that cuts across two or more lines. Before using parallel-line rules, keep basic facts ready: angles on a straight line add to 180∘180^\circ180∘, vertically opposite angles are equal, and angles in a triangle add to 180∘180^\circ180∘.
In a written solution, each new angle needs a reason. Common reasons include angles on a straight line, vertically opposite, corresponding, alternate, co-interior, and angles in a triangle.
Question 1
3 marksAB AB\,AB and CD CD\,CD are parallel. Angle HIK=75∘HIK = 75^\circHIK=75∘ Angle BFH=40∘BFH = 40^\circBFH=40∘
What is the angle sum on a straight line?
Revision notes for WJEC GCSE Maths Angles in Parallel Lines: explanations and worked examples.
1 of 4
Two parallel lines are cut by a transversal. The top-right angle at the upper intersection is 72∘72^\circ72∘, and xxx is the top-right angle at the lower intersection. What is xxx?