IN this school-book of three hundred and twenty-six pages the authors have arranged a course on trigonometry which should be most useful to those studying this subject for the first time. The book ...

Parallax is the observed displacement of an object caused by the change of the observer's point of view. In astronomy, it is an irreplaceable tool for calculating distances of far away stars.

The average distance between the Earth and Sun measured using trigonometry is 93 million miles, not 3,000 miles as claimed in a viral post online.