Assertion: ellipse's vertex | /r/HasProperty | the distance
Facets:
Source sentences:
text: is a vertex of the ellipse, the distance from ( − c , 0 )
text: If \((a,0)\) is a vertex of the ellipse, the distance from \((−c,0)\) to \((a,0)\) is \(a−(−c)=a+c\).