Lines Flashcards
normal vector
a non-zero vector that is orthogonal to a given line, 𝓁, (or later a vector perpendicular to a given object)
n = [a,b]
𝓁
a line in R²
P
a point on a line 𝓁
p
a position vector for the point P
normal vector approach
involves using n • (x-p) = 0 or n • x = n • p
which produces the general equation ax + by = c for a line or R²
this equation is made because x-p is a direction vector and n is a normal vector or a line orthogonal to that vector, ∴ the dot product of these two must be 0
d
a direction vector for 𝓁 (≠0)
direction vector approach
involves the vector equation x = p + td
where x is the vector [x,y], p is a point on the line, d is a direction vector for the line and ≠0, and t is some constant.
parametric equations
equations that split a vector into each of its components in the form of x = p₁ + td₁, y = p₂ + td₂
a vector that satisfies each of these equations can be used. t is a parameter
parameter
A variable that is to take different values, thereby giving different values to certain other variables.
ex. t in parametric equations
n and d are
orthogonal