subtend
/səbˈtend/verb
with obj.
1
- (of a line, arc, or figure) form (an angle) at a particular point when straight lines from its extremities are joined at that point（线, 弧, 图形）对向。
1.1
- (of an angle or chord) have bounding lines or points that meet or coincide with those of (a line or arc)（角或弦）被一条直线（或弧）所截（或所限）。
2
- Botany (of a bract) extend under (a flower) so as to support or enfold it【植】衬托。
词源
late 16th cent. (in sense 1)： from Latin subtendere, from sub- 'under' + tendere 'stretch'. Sense 2 dates from the late 19th cent.