# Help, Parametric and vector eqns of a lines

well, im lost...im not sure if this goes in college or k-12, but im in grade 12 in canada...and im learning here, so i guess im at the right place,
any wyas....i need help, with parametric and vector eqns of lines, since im failing this course horribly...my teacher sucks and marks hard and I dont get anything!...
so now for the questions

The angle ø, 0° < ø < 180°, That a line makes with the positive x-axis is called the angle of inclination of hte line.

A) find the angel of inclination of each of hte following lines.
_
i) r = (2,-6) + t(3,-4) ii) r = (6,1) + t(5,1)

B) prove that the tange of the angle of inclination is equal to the slope of hte line.

Related Introductory Physics Homework Help News on Phys.org
robphy
Homework Helper
Gold Member
that didnt help me even a remote bit...still lost....:(

robphy
Homework Helper
Gold Member
Plot r(t) on a graph (t along the horizontal axis, r along the vertical axis).
Choose two values of t (say t=0 and t=1)
Evaluate r at t=0. That gives you a point P with coordinates (t,r)=( 0, r(0) ).
Evaluate r at t=1. That gives you a point Q with coordinates (t,r)=( 1, r(1) ).
Calculate the slope of the line segment PQ.

Now think of PQ as the hypotenuse of a right triangle,
with one leg parallel to the horizontal t-axis
and the other leg parallel to the vertical r-axis.
The angle of inclination is an angle of that triangle.
Use trigonometry to relate that angle to your triangle legs and the slope.