Point f is on circle c. Circle c is shown. Line segments e c, f c, and d c are radii. Tangents e g and d g intersect at point d outside of the circle. A line is drawn to connect points f and g. The length of g e is 10 and the length of e c is 7. 5. Angles e and d are right angles. What is the length of line segment gf? 12. 5 units 15. 0 units 17. 5 units 20. 0 units.