subtend

Etymology

From Latin subtendere, from sub (“under”) + tendere (“to stretch, extend”). See tend.

verb

1. (transitive, mathematics) To use an angle to delimit (mark off, enclose) part of a straight or curved line, for example an arc or the opposite side of a triangle.
   A 43° angle subtends an arc of about 0.75 meters on a circle with a radius of 1 meter.
2. (transitive, also mathematics) To extend or stretch opposite something; to be part of a straight or curved line that is opposite to and delimits an angle.
   A hypotenuse subtends the right angle of a right triangle.
   An arc measuring about 0.75 meters on a circle with a radius of 1 meter subtends an angle of about 43°.
   ...trillions of bacteria, each equally an individual, which are found in a person’s gut, his mouth, his scalp, his skin and all of the crevices and orifices that subtend from his body’s surface. 16 August 2012, “Me, myself, us”, in The Economist, issue
3. (transitive, mathematics) To form the central angle of a circle underneath an arc
   The points A and B on the circumference form the arc AB, which subtends the central angle θ.