Answer:
Step-by-step explanation:
Parameterize the ellipse as (acos∙,bsin∙). Take points P:=(acosp,bsinp) and Q:=(acosq,bsinq) on the ellipse, with midpoint M:=(P+Q)/2.
If |PQ|=2k, then
a2(cosp−cosq)2+b2(sinp−sinq)2=4k2
The coordinates of M are
xy==a2(cosp+cosq)b2(sinp+sinq)
