Solve the Problem $s ( t ) = - 3 \cos 7 t$

Multiple Choice

Solve the problem.
-The position of a weight attached to a spring is $s ( t ) = - 3 \cos 7 t$ inches after $t$ seconds. What are the frequency and period of the system?

A) Frequency $= 7$ cycles per sec, period $= \frac { 1 } { 7 } \mathrm { sec }$
B) Frequency $= \frac { 7 } { \pi }$ cycles per sec, period $= \frac { \pi } { 7 } \mathrm { sec }$
C) Frequency $= \frac { 7 } { 2 \pi }$ cycles per sec, period $= \frac { 2 \pi } { 7 } \mathrm { sec }$
D) Frequency $= \frac { \pi } { 7 }$ cycles per sec, period $= \frac { 7 } { \pi } \mathrm { sec }$