draw a square with side length of 4. all four angles are 90 degrees and all four sides are 4.
then draw a rectangle with length of 9 and with of 2. all four angles would be 90 degrees, but the proportion of the 2 sides are different when compared to the sides of the square.
y = 3x
• parallel lines have equal slopes.
the equation of a line passing through the origin (0, 0) is
y = mx ( m is the slope )
here m = 3, hence
y = 3x ← equation of parallel line