Math Help - Calculus III Vector problem

1. Calculus III Vector problem

If anyone could help me with this I would really appreciate it.

If vector u1 and vector u2 are orthogonal unit vectors and vector v=A(u1)+B(u2) find v dot u1

I know that because u1 and u2 are orthogonal their dot product is equal to zero, but I'm not sure what to do beyond that.

Thank you!

2. Originally Posted by vcf323
If anyone could help me with this I would really appreciate it.

If vector u1 and vector u2 are orthogonal unit vectors and vector v=A(u1)+B(u2) find v dot u1

I know that because u1 and u2 are orthogonal their dot product is equal to zero, but I'm not sure what to do beyond that.

Thank you!
$v = A(u_1) + B(u_2)$

$v \cdot u_1 = [A(u_1) + B(u_2)] \cdot u_1 = A(u_1) \cdot u_1 + B(u_2) \cdot u_1 = A(u_1) \cdot u_1$

to finish ... what is the unit vector $u_1$ "dotted" with itself ?