# PPI Camara Practice Problem 98



## bripgilb (Apr 9, 2018)

Ladies and Gents,

Was working out this practice problem in PPI Camara.  Problem #98.

I got 100degrees.

Looking through the solution I see that they put: (cos(180))=0...  well I got: cos(180)=-1

Thoughts?  Please, see references.






AND GOOD LUCK TO ALL OF THOSE TAKING THE EXAM THIS FRIDAY!

Thanks,

Brip


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## bobbilly (Apr 10, 2018)

I got the same thing as you but cos^-1(-0.4659) = 117 degrees.

https://www.wolframalpha.com/input/?i=.17+%3D+(1%2Fpi)+*+integral+from+X+to+pi+of+sin(theta) Answer is 2.055 radians which is 117 degrees


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## jshar17 (Apr 11, 2018)

Check the errata on ppi's site. It's updated for 120deg. This integral can be quickly done with TI 36x pro or equiv.


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## bobbilly (Apr 11, 2018)

Since we are on the topic of rectifiers, if this was a half wave rectifier we would need to change 1/pi to 1/(2*pi)??


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## helphere (Apr 11, 2018)

bobbilly said:


> Since we are on the topic of rectifiers, if this was a half wave rectifier we would need to change 1/pi to 1/(2*pi)??


yes


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