Latitude exact relationship of parallels and meridians with horizontal and vertical: both are complicated curves. On the sphere the normal passes through the centre and the latitude () is therefore equal to the angle subtended at the centre by the meridian arc from the equator to the point concerned. If the meridian distance is denoted by then where denotes the mean radius of the Earth. is equal to . No higher accuracy is appropriate for since higher-precision results necessitate an ellipsoid model. With this value for the meridian length of 1 degree of latitude on the sphere is (60.0 nautical miles).
Latitude ON a customizable, Linux-based Mobile Internet Device (MID) platform the laptop is able to boot almost instantly and view Email, document reader, calendar, contacts and access the Internet. First laptop models to include Latitude ON were E4200 and E4300 released in February 2009. Last laptop model introduced so far is Latitude Z600. Dell claims that battery life can be extended to days. Latitude ON Reader is similar to Dell's MediaDirect where the software is located in a separate partition on the system hard drive and has a dedicated button to power on. There are several versions of Latitude ON: Latitude ON