# Engineering General Second-order Circuit

#### paulmdrdo

Homework Statement
Find the expression for $v(t)$
Homework Equations
SEE ATTACHED PHOTO
I was trying to follow the solution for this problem and got stuck in the last portion of the solution. I encircled the part that I did not understand. I can't figure out how the solver was able to come up with tangent terms. Please enlighten me. TIA

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#### NascentOxygen

Mentor
The author equated eqn (2) to 0
then extracted (and divided both sides by) the common factor 5(cos 21.749t)

"General Second-order Circuit"

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