Why is 6 a triangle number dot diagram

On a architect's drawing of a house, 1 inche representa 1.5

Choose the equation below that represents the line that passes through the point (2, 4) and has a slope of 3. a) y − 4 = 3(x − 2) b) y − 2 = 3(x − 4) c) y + 4 = 3(x + 2) d) y + 2 = 3(x + 4)

What is perpendicular to y=-1/2x+11