Angles  »      

1. Angles on a straight line
2. Vertically opposite angles
Two straight lines g and h intersect.
This results in four angles whose measures
are labeled α, β, γ and δ.

Which of the statements on the right are correct?

To find the solution, you can touch the
straight lines at the black points
and move them.


Vertically opposite angles
β and δ have always the same measure.
α and δ have always the same measure.
If α = 90° ⇒ all angle measures are equal.
Opposite angles are equal in measure.
If α = 75°, then β is twice as large.
If β = 60°, then γ is twice as large.
All four angles never have equal measure.
α and β always add up to 180°.
   

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