Question

The angle of 1" (second of arc) in a radian is equal to:
 

(1) 4.85 × 10^–4
(2) 4.85 × 10^–6
(3) 1.75 × 10^–2
(4) 1.75 × 10^–4

Answer 1

A minute of arc is \(π\over 10800\) of a radian.

A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol ″, is \(1\over60\) of an arcminute, \(1\over3600\) of a degree, \(1\over1296000 \)of a turn, and \(π\over648000\) (about \(1\over206369\))

so answer is,

(2) 4.85 × 10^–6