Basic rules
Complementary angles
Complementary angles are a pair of angles that add to 90 degrees
You can see in the video that DBA = 68.2 and CBD = 21.8
68.2 + 21.8 = 90
Therefore the angles are complementary
Use the angle tool to find all angles that are complementary
Which angles are complementary?
Supplementary angles
Supplementary angles are a pair of angles that add to 180 degrees
You can see in the video that DBA = 75.96 and CBD =104.04
75.96 + 104.04 = 180
Therefore the angles are supplementary
Which pairs of angles are supplementary?
Angles in a Triangle
All three angles inside a triangle add to 180 degrees
You can see in the video that the three interior angles are:
CAB = 27.05
ABC = 114.17
BCA = 38.78
27.05 + 114.17 + 38.78 = 180
Find the missing angle CBA
Use what you have learnt to find EFC
Angles on a line add to 180 degrees
Go to this transum website to have a go:
https://www.transum.org/Software/SW/Starter_of_the_day/Students/AnglePoints.asp?Level=2
Angles at a point
Move any point around and watch how the angles change. But what do you notice about the sum of the angles?
What is the value of FBE?
For more questions complete this activity:
https://www.transum.org/Software/SW/Starter_of_the_day/Students/AnglePoints.asp