William Chapple (surveyor)

William Chapple (1718–1781) was an English surveyor and mathematician. His mathematical discoveries were mostly in plane geometry and include:

• the first proof of the existence of the orthocentre of a triangle,
• a formula for the distance between the incentre and circumcentre of a triangle,
• the discovery of Poncelet's porism on triangles with a common incircle and circumcircle.

He was also one of the earliest mathematicians to calculate the values of annuities.