Straight-line graphs

Question 1

Line length

Answer 1

root((x₂-x₁)²+(y₂-y₁)²)

Question 2

Gradient

Answer 2

(y₂-y₁)/x₂-x₁

Question 3

Midpoint

Answer 3

((x₂+x₁)/2,(y₂+y₁)/2)

Question 4

Parallel lines

Answer 4

m -> m

Question 5

Perpendicular lines

Answer 5

m -> -m^-1

Question 6

What is standard form?

Answer 6

ax+by+c = 0 where a, b and c are integers and a > 0. The y intercept is c/b and the gradient -a/b