Vecto Calculus

[Electro]

Greetings everyone,

I have a problem: "Consider the curves r1(t)=(t, 1-t, 16+t^2) and
r2(t)=(8-s,s-7, s^2)
a) At what point do they meet?
b) Find their angle of intersection

The first part is easy, but I'm encountering some problems with b). To find the angle we need to apply the formula |n||m| cos(a)=n.m
The point is that we dont have the values of n and m. I tried to subsitute values for t and s (we also know the point of intersection) but still couldn't get it.
Someone can help?
Thanks

[bomba923]

Apply that formula |n||m| cos(a)=n.m where n and m are the unit tangent vectors of r1 & r2 at the point of intersection.

[Electro]

If we get the Unit Tangent Vectors then they are in terms of t. What do we substitute for t to get the value? The point we have is (3,-2,25) ->(x,y,z).