How is trigonometry used in astronomy?
Trigonometry is essential for astronomy, Besides 2-D trigonometry relating to triangles, spherical trigonometry, relating to spherical triangles, is also important in astronomy.
The planets' surfaces are nearly spherical.
Points on surface can be spotted by using spherical polar co-ordinates
Three great circles on the planet's surface form a spherical triangle. . Spherical trigonometry formulas connect the lengths of arcs of this triangle with the angles of the triangle. There is similarity between these formulas and 2-D formulas.
The ships over seas and the planes, at the top altitudes, trace nets of spherical triangles..