In a mathematical sense, the curvature is the reciprocal of the radius, so that a smaller curvature implies a large radius. A curve of large radius, as for a railway, cannot be laid out by using the radius directly. We will see how the problem of laying out a curve of large radius is solved.
In 1983, Motorola released its first commercial mobile phone, known as the Motorola DynaTAC 8000X. The handset offered 30 minutes of talk-time, six hours standby, and could store 30 phone numbers. It also cost Â£2639 ($3995). In the very early days of the mobile space handsets werenât designed with consumers in mind.
The idea of a mobile phone had been around since the 1920's when police radios were in use. Finally, in 1973 Dr. Martin Cooper of Motorola created a cell phone that was usable. It was sold to government projects/offices and in 1984 the first cell was sold to the general public.