# Math Help - Need To Remember Solving These exercises! - Help!

1. ## Need To Remember Solving These exercises! - Help!

It's been quite a while since i last have tried to solve these exercises for college.
Can someone try to re-explain them to me along with the progressive solutions and calculus, please?

Here they are
1) Let B={e1=(2,1,3), e2=(1,0,1), e3=(1,1,1)}, find:
a) B- Basis of the vector space R(to the third)
b) expression of vector x=(2,0,3) with respect to basis B
2) Let A(1,0,0), B(0,3,0), C(0,0,2). Calculate the volume of the tetrahedron OABC and it's altitude from A.
3) Let A,B,C - as above :
a) equation of plane (ABC)
b)the projection of 0(0,0,0) onto the plane (ABC)
4) Find the equation of the surface obtained by rotating the curve :

(C)-|y=sinx
|z=0 around (d)=0x
5)Determine the tangent and the normal line to {x=4-sint and {y=1-cost, t belonging to [0, 2π] at A(t=π/2)
and:
6) Determine the curvature and the torsion of
(C)r(t)= costi(vector)+sintj(vector)+tk(vector) at (0,1,π/2) t belonging to R

2. We are not a homework service. Show that you've at least tried to solve these and exactly where you are stuck.