Circle of latitude can be calculated by a common sine or cosine function. The 60th parallel north or south is half as long as the Equator (disregarding Earth's minor flattening by 0.3%). A circle of latitude is perpendicular to all meridians. The latitude of the circle is approximately the angle between the Equator and the circle, with the angle's vertex at Earth's centre. The equator is at 0°, and the North Pole and South Pole are at 90° north and 90° south, respectively. The Equator is the longest circle of latitude and is the only circle of latitude which also is a great
Dell Latitude the C6x0, D6x0, and E64x0 lines, but as of 2015 this line has been discontinued and replaced by both the 5 series and the 7 series. The 15" "Premium" line was the 8 series, until the E-series merged this line with the 6 series (Model numbers being along the lines of C8x0 or D8x0). The "budget" line was the 5 series, but as of 2015 the 5 series and 7 series Latitude laptops are the primary lines of Latitude laptops. The 3 series has replaced the 5 series as the budget line. Dell has also since dropped the E from