Question

Period of $f\left(x\right)=\cos (7x-5)$ is

• A. $\frac{2\pi -5}{7}$
• B. $2\pi -5$
• C. $\frac{2\pi }{7}$
• D. $\frac{\pi }{7}$

Answer 1

The correct option is C $\frac{2\pi }{7}$

We know that period of $\cos x$ is $2\pi .$
Period of $f\left(x\right)=\cos (ax+b)$ is $\frac{2\pi }{|a|}$
So, period of $f\left(x\right)=\cos (7x-5)=\frac{2\pi }{7}$