subtend
sub.tend \s*b-'tend\ vt [L subtendere to stretch beneath, fr. sub- +
tendere to stret]ch - more at THIN 1a: to be opposite to {a hypotenuse ~s a
right angle} 1b: to extend under and mark off or enclose {a chord ~s an a
rc} 2: to underlie so as to include
Webster's English Dictionary