What is the period of the function h(x)=cos(4x/5)?

Correct Answer is : 5π25π /225π

Correct Answer is : 5π25π /225π

Test Index

UPSC NDA 2 2019 Mathematics Solved Paper

Question Numbers: 86-88

Directions: Read the following information and answer the three items that follow:

Consider the function f(x) = g(x) + h(x)

Question : 87 of 120

Marks: +1, -0

h(x)=cos(\frac{4x}{5})

Solution:

Concept:

The period of

\cos(ax)

\frac{2\pi}{|a|}

Explanation:

Given

h(x) = \cos\left(\frac{4x}{5}\right)

Here,

a = \frac{4}{5}

The period is

\frac{2\pi}{4/5} = \frac{2\pi \times 5}{4} = \frac{5\pi}{2}

Answer:

\frac{5\pi}{2}

(Option C).

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