SOLUTION: 5) Find the period of f(x) = 3 - 2cos(3x+pi) a) 2 pi / 3 b) Pi / 3 c) Pi / 6 d) Pi e) 2 pi

Algebra ->  Trigonometry-basics -> SOLUTION: 5) Find the period of f(x) = 3 - 2cos(3x+pi) a) 2 pi / 3 b) Pi / 3 c) Pi / 6 d) Pi e) 2 pi      Log On


   

Question 121954: 5) Find the period of f(x) = 3 - 2cos(3x+pi)
a) 2 pi / 3
b) Pi / 3
c) Pi / 6
d) Pi
e) 2 pi
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

The general form of cosine is:
y+=+Acos%28Bx+%2B+C%29+%2B+D
where the period T=2pi%2FB+

So for the trig function f%28x%29=3+-+2cos%283x%2Bpi%29 which also looks like f%28x%29=+-+2cos%283x%2Bpi%29%2B3. Notice how 3x matches up with Bx, so Bx=3x which means B=3

T=2pi%2F3+ Now simply plug in B=3 into the period formula

So the period is T=2pi%2F3+

So the answer is A)