The Tropic of Cancer and Capricorn are imaginary lines of latitude running parallel with the Equator. Both are 23.5 degrees north and south of it, Cancer in the north, Capricorn in the south, so they are 47 degrees apart. It is at these boundaries that the sun is directly overhead at noon during the winter and summer solstices, Capricorn denoting the sun's position during the winter solstice and Cancer denoting its position during the summer solstice. The area bounded by both lines is considered the "tropics" because there's no seasonal variation to the weather.
The Tropic of Cancer is the latitude 23° 26′ 22″ degrees North of the Equator and the Tropic of Capricorn is the latitude 23° 26′ 22″ South of the Equator. So, totally 46° 52' 44" separate the Tropic of Cancer from the Tropic of Capricorn.
However, to be very precise and accurate the position of both these latitudes is not fixed and varies in a very complicated manner over a period of time.
In the Tropics the sun reaches a point directly overhead and a point directly underneath at least once during every solar year.