Area of a circle order to arrive at the formula for the area of a disk. Consider unwrapping the concentric circles to straight strips. This will form a right angled triangle with r as its height and 2r (being the outer slice of onion) as its base. Finding the area of this triangle will give the area of the disk The opposite and adjacent angles for this triangle are respectively in degrees 9.0430611..., 80.956939... and in radians 0.1578311... , 1.4129651... Explicitly, we imagine dividing up a circle into triangles, each with a height equal to the circle's radius and a base that is infinitesimally
Outer Circle railway line Belgrave and Lilydale lines) with Oakleigh station to the south, via Riversdale on what is now the Alamein line. The final section was north from Riversdale through to Fairfield station (then called Fairfield Park station). There was also a branch line from the closed Waverley Road station (near the modern East Malvern station) to Darling and Burnley. This was the first section of what is now the Glen Waverley line and was opened a few weeks before the Outer Circle. When opened the line was in length, and had 11 stations, all provided with twin platforms and crossing loops. Provision