20 rows * 15 seats per row=300 seats in section J
300 seat in Section J * $18 per ticket= $5,400 in revenue
The answer is 0.003021148
CPCTC means the corresponding parts of congruent triangle that are congruent.
So, angle GAE is approximately equal to angle GEA.
Recall the Maclaurin expansion for cos(x), valid for all real x :

Then replacing x with √5 x (I'm assuming you mean √5 times x, and not √(5x)) gives

The first 3 terms of the series are

and the general n-th term is as shown in the series.
In case you did mean cos(√(5x)), we would instead end up with

which amounts to replacing the x with √x in the expansion of cos(√5 x) :
