# Second Order Circuit Question

#### Digit0001

Joined Mar 28, 2010
100
Hi

Can someone explain to me how they got tan() in the last couple of lines, when they are finding the peak time.
View attachment tut7_sols.doc

P.S

#### jegues

Joined Sep 13, 2010
733
Hi

Can someone explain to me how they got tan() in the last couple of lines, when they are finding the peak time.
View attachment 30770

P.S
It seems as though they took the expression for $$\frac{dv_{c}}{dt}$$ (i.e. equation (2)), and divided it by, $$-5cos(21.794t_{o}),$$ which is reasonable because the other side of the equation is simply 0.

I assume they are neglecting the exponential terms because $$t_{o}$$ is very small. By this I mean,

$$e^{t_{o}}, \quad t_{o} \approx 0 \Rightarrow e^{t_{o}} \approx 1$$