Work done with force perpendicular to path in electric potential

[ElectricSenpai]

For the diagram below, is it wrong?
They have calculated the work done from i to f, using the force that is cross sectional to the particle.
Shouldn't the force in the direction of the path be the the force x cos theta.
They have summed the force that is not in the direction of the path?

 

[ElectricSenpai]

So the summation should be:i to f INT(Q0. E . Cos theta) ds

 

[jim hardy]

Back to basic math -

dot product of vectors is not same as dot in algebraic multiplication ?

doesn't dot product of vectors include cosine of angle between them?

https://en.wikipedia.org/wiki/Dot_product

 

[ElectricSenpai]

Oh yeah thanks.

 

[Windadct]

Haha -- dot product of vectors = basic math ... only in PF.