How would I find a ⋅ b?

a = 8i + 6j, b = 4i + 5j

I don't think that I can use
dot products to find this, and since they are 2D vectors I'm not sure how to use cross products here.

Question

How would I find a ⋅ b?

a = 8i + 6j, b = 4i + 5j

I don't think that I can use 
dot products to find this, and since they are 2D vectors I'm not sure how to use cross products here.

sshayer · Answer

a.b=(8i+6j).(4i+5j)=8(4)+6(5)=?

sshayer · Answer

$$a \times b=\left|\begin{matrix}i & j&k \ 8 & 6&0\4&5&0\end{matrix}\right|=?$$

sshayer · Answer

=0i-0j+[8(5)-6(4)}k
=16k

phi · Answer

It looks like a dot product to me.  what makes you think it is not ?

phi · Answer

I treat 8i+6j as completely equivalent to <8,6> i.e. the x component is 8, the "y" component is 6 and <8,6> dot <4,5>= 32+30= 62 (just a scalar number)

phi · Answer

It looks like a dot product to me.  what makes you think it is not ?