get the dimensions of a video screen given its diagonal length

diag_len.py

import sys, math

if len(sys.argv) != 2:
	print 'provide a diagonal length'
	exit(0)

diag = float(sys.argv[1])

# x*x + y*y = diag^2
# x*ar = y
# x*x + ar*ar*x*x = diag^2
# (1+ar*ar)*x*x = diag^2
ar = 16.0 / 9.0
s = pow(diag, 2.0) / (1.0 + pow(ar, 2.0))
x = math.sqrt(s)
y = ar * x
print round(x, 1), '\t', round(y, 1)