Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If x is a real quantity, what is the minimum value of $\left(25 \cos ^2 x+9 \sec ^2 x\right)$

Options:

30

20

15

40

Correct Answer:

30

Explanation:

Concept we are using here is :-

If we are given  acos²x + bsec²x , then

Minimum value of acos²x + bsec²x  is  2\(\sqrt {ab }\).

ATQ,

Minimum value of

25cos²x + 9sec²x

= 2\(\sqrt {25 ×9 }\)

= 30