- #1
WeiLoong
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Homework Statement
if a =3i-4j
find a unit vector perpendicular a
Homework Equations
Vector
The Attempt at a Solution
<a> = <3 , -4>
<n> = <x, y> : x² + y² = 1
<a>•<n> = 3x-4y = 0
y = (3/4)x
x² + (9/16)x² = 1
25x² = 16
x = -4/5, 4/5
y = -3/5, 3/5
There are two unit vectors normal to a which have opposite directions:
n =(4i + 3j)/5
and
n = -(4i+3j)/5
This is the answer that given by my textbook. Can somebody explain to me the 2nd step <n> = <x, y> : x² + y² = 1
I do not understand why it use x^2+y^2=1 as this is circle equation.