Permalink Submitted by Cecil Burrow on June 3, 2017

> Euclidean geometers however only recognise angles between straight lines.

Geometers in general only recognize angles between straight line - the angle between curves is typically defined as the angles between their tangent lines. Understood this way, the example of a diameter cutting a circle is *not* a counterexample to the postulate in question.

## > Euclidean geometers however

> Euclidean geometers however only recognise angles between straight lines.

Geometers in general only recognize angles between straight line - the angle between curves is typically defined as the angles between their tangent lines. Understood this way, the example of a diameter cutting a circle is *not* a counterexample to the postulate in question.