__ __ __ if ab upside down t df, then df || t. true false

If line t is a tangent to the circle, then angle ABT is a 90 degree angle (point T is some point on line t that isn't B). By the converse of the corresponding angles theorem, this means DF is parallel to line t. So the claim is true. Again this all hinges on if line t is a tangent to the circle. 

Side Note: The upside down T symbol means "perpendicular to"

A. -10 is the value of x