Cram for the PE - Exam 1 - Problem 16

[dateng]

Hi, does anyone happen to know how the solution is derived? It looks like the entire solution was lumped into a single equation?

Unless I am mistaken, and the solution with formulas for R and X are standard formulas?
I know that Vpu^2 / (P^2+Q^2) = z, since z = V / S (and in this case, S was squared to remove that square root). Other than that, I am lost as to how the solution was obtained. Could someone offer some insight please?

 

[lturner]

I think this question was written when it was pencil/paper and open book. I know I don't have those R and X equations memorized nor are they on the reference handbook.

I solved it this way. When in doubt, I start drawing triangles.

 

[akyip]

Attached is how I solved this problem from Cram for Exam Vol.1.

I recommend not trying to memorize this formula (since the exam is now CBT and closed-book except for the provided references), but instead learn to derive from basic/fundamental equations.

 

[dateng]

Thanks so much! Your solutions helped me make more sense of this problem.