Triangulation
![Triangulation of Kodiak Island in 1929.](/Images/godic/202502/17/Theb1604_-_Flickr_-_NOAA_Photo_Library0242.jpg")
![Triangulation may be used to calculate the coordinates and distance from the shore to the ship. The observer at A measures the angle α between the shore and the ship, and the observer at B does likewise for β . With the distance between A and B or the coordinates of A and B known, then the law of sines can be applied to find the coordinates of the ship and the distance d.](/Images/godic/202502/17/Triangulation-boat0242.png")
![Liu Hui (c. 263), How to measure the height of a sea island. Illustration from an edition of 1726](/Images/godic/202502/17/Sea_island_survey0242.jpg")
![Gemma Frisius's 1533 proposal to use triangulation for mapmaking](/Images/godic/202502/17/G-F_triangulation0242.jpg")
In trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly (trilateration). The point can then be fixed as the third point of a triangle with one known side and two known angles.