the question says:
calculate the magnitude and direction of the acceleration of a particle that moves so that its position vector in metres is given by
r=(8t-24^2)i + (6+4t-t^2)
where t is time in seconds.
I think i have worked out the acceleration to be -4i -2j
and so as a result is the magnitude is 4.47
but i am unsure how to work out direction. My teacher whipped through it and so i got lost... can you help please?