Secant line point a "tangent line" and in no points an "exterior line". A "chord" of a circle is the line segment that joins two distinct points of the circle. A chord is therefore contained in a unique secant line and each secant line determines a unique chord. In rigorous modern treatments of plane geometry, results that seem obvious and were assumed (without statement) by Euclid in his treatment, are usually proved. For instance, "Theorem (Elementary Circular Continuity)": If formula_1 is a circle and formula_2 a line that contains a point that is inside formula_1 and a point that is outside of
Circle MRT line road was temporarily closed to traffic. On 20 September 2011, a power fault disrupted train services on all 16 stations on the Circle line. The four hours delay left thousands of commuters stranded during rush-hour. It was reported that leaks and a damaged electrical cable along the Circle line were the cause of the disruption. The disruption started at about 5.30 am. Train services were gradually restored from 8am and all services were restored just before 10am. Dakota and Mountbatten stations were the last two to resume operations. Investigations were carried out. It was later found that a faulty cable