My "geometry English" is not good so I hope you can understand from picture.

Attachment 30687

I need to prove that EFGH is tangential. Angles DHS,DGS,CFS,AES are right angles. Thanks.

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- April 16th 2014, 08:47 AMkicmaCyclic quadrilateral & tangential quadrilateral proof
My "geometry English" is not good so I hope you can understand from picture.

Attachment 30687

I need to prove that EFGH is tangential. Angles DHS,DGS,CFS,AES are right angles. Thanks. - April 18th 2014, 11:32 AMearbothRe: Cyclic quadrilateral & tangential quadrilateral proof
Hello,

I don't understand what is meant by your drawing. I've attached a sekant-tangent-quadrilateral:

Attachment 30706

Please tell us which point is your point S: The crosspoint of the red sekants or the midpoint of the inner circle ? - April 18th 2014, 12:43 PMjohngRe: Cyclic quadrilateral & tangential quadrilateral proof
Hi,

I think I understand your question. Here's a solution:

http://i58.tinypic.com/1g5c34.png