# Cram for the PE - Exam 1 - Problem 16



## dateng (Mar 7, 2021)

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?


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## lturner (Mar 7, 2021)

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.


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## akyip (Mar 8, 2021)

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.


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## dateng (Mar 15, 2021)

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


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