One line passes through the points (1,9) and (2,6), and another line passes through (3,3) and (-1,5). Determine the acute angle between the two lines.
slope of first line = m1 = (6-9)/(2-1) = -3
slope m2 = (5-3)/(3+1) = 1/2
if Ø is the angle between them:
tanØ = (m2-m1)/(1 + m2m1)
= (1/2 - 3)/(1 + (1/2)(-3))
= (-5/2) / (-1/2) = 5
Ø = 78.7° to the nearest tenth