Assertion: ellipse's foci | /r/HasProperty | ± 33
Facets:
Source sentences:
text: + y 2 49 = 1 ; center: ( 0 , 0 ) ; vertices: ( 0 , ± 7 ) ; co-vertices: ( ± 4 , 0 ) ; foci: ( 0 , ± 33 )