In the applications with which we are concerned, t, n are very small quantities; and we may take P = x yn - At the same time dS may be identified with dxdy, and in the de nominator p may be treated as constant and equal to f.
The old British tower and castle were called Castell caled fryn yn Rhos, the "castle of the hard hill in Rhos."
In the geometry of plane curves, the term parabola is often used to denote the curves given by the general equation a' n x n = ym+n, thus ax= y 2 is the quadratic or Apollonian parabola; a 2 x = y 3 is the cubic parabola, a 3 x = y4 is the biquadratic parabola; semi parabolas have the general equation ax n-1 = yn, thus ax e = y 3 is the semicubical parabola and ax 3 = y 4 the semibiquadratic parabola.
The nasal mutation occurs after fy, " my," and yn, " in "; thus fy mhen, " my head " (pen, " head "), yn Nhalgarth, " at Talgarth."
Near Wrexham, but in a detached portion of Flintshire, to the S.E., is Bangor-is-coed (Bangor yn Maelor), the site of the most ancient monastery in the kingdom, founded before r80; some 1200 monks were slain here by IEthelfrith of Northumbria, who also spoiled the monastery.