Help with a proof

[supergurl21]

I am having trouble with proofs and i was wondering if someone could solve this problem for me.

Prove that tangents to a circle at the endpoints of a diameter are parallel. State what is given, what is proved, and your plan for proof. Then write a two-column proof.

 

[galactus]

Truthfully, I always hated these silly geometric proofs, too.

Start off by drawing your circle and tangent lines, label what is given and what you are to prove.

Lines AB and CD are tangent to the circle with center O at points E and F.

Line segment EF is the diameter of the circle.

Prove: line AB is parallel to line CD.

Use the parallel line law which states 2 lines that are perpendicular to the same line are parallel.

Here are a few statements you could use:

1. line EF is the diamater of the circle.
2. Lines OB and OD are radii.
3.lines AB and CD are tangent to the circle.

Add a few more and the proof should be complete. Can you finish?.