1. ## vectors

just needed a clue on how to start the math behind this thanks!!
find a unit vector, if terminal point is at (4,4) on 4y=x^2, is normal to the curve and pointed towards the positive y-axis

2. Originally Posted by rabih2011
just needed a clue on how to start the math behind this thanks!!
find a unit vector, if terminal point is at (4,4) on 4y=x^2, is normal to the curve and pointed towards the positive y-axis
I hope that I understand your question correctly this time ..

Here are the steps to perform:

1. Determine the gradient m of the curve at P(4, 4).
2. Determine the orthogonal direction n of the gradient using $m\cdot n = -1$
3. n can be written as a vector $\vec n = (1, n)$. Determine the length of $\vec n$ and consequently
4. Calculate the unit vector of $\vec n$