What Conditions on c, d, e Fill a Dashed Triangle Using Vectors u, v, w?

[scarebyte]

Homework Statement

Under what restrictions on c,d,e will the combinations c*u+d*v+e*w fill in the dashed triangle?

Homework Equations

The Attempt at a Solution

I think c,d,e>=0 and bcos the triangle it's in a plane maybe remove one of c,d or e doing c+d+e=number?

 

[mutton]

The midpoint between u and v is (u + v)/2. Convince yourself by drawing a parallelogram. This fact can be used to find conditions on c, d such that the linear combinations cu + dv fill in the line segment between u and v.

A better way to think about this: The vector from u to v is v - u. Starting at u, we can vary the length of v - u to fill in the line segment. Consider u + t(v - u) for t in [0, 1].

To fill in the entire triangle including its inside, use the same sort of reasoning: Starting at u, we can vary the lengths of v - u and w - u under certain restrictions.