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State whether the following are true or false. Justify your answer. sec A = 125 for some value of angle A. - Mathematics

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Question

State whether the following are true or false. Justify your answer.

sec A = `12/5` for some value of angle A.

Options

  • True

  • False

MCQ
True or False
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Solution

This statement is True.

Explanation:

sec A = `12/5`

`"Hypotenuse"/"Side adjacent to ∠A" -  12/5`

`("AC")/("AB") = (12/5)`

Let AC be 12k, AB will be 5k, where k is a positive integer.

Applying Pythagoras theorem in ΔABC, we obtain

AC2 = AB2 + BC2

(12k)2 = (5k)2 + BC2

144k2 = 25k2 + BC2

BC2 = 119k2

BC = 10.9k

It can be observed that for given two sides AC = 12k and AB = 5k,

BC should be such that,

AC − AB < BC < AC + AB

12k − 5k < BC < 12k + 5k

7k < BC < 17 k

However, BC = 10.9k

Clearly, such a triangle is possible and hence, such value of sec A is possible.    

Hence, the given statement is true.

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Chapter 8: Introduction to Trigonometry - Exercise 8.1 [Page 181]

APPEARS IN

NCERT Mathematics [English] Class 10
Chapter 8 Introduction to Trigonometry
Exercise 8.1 | Q 11.2 | Page 181
RD Sharma Mathematics [English] Class 10
Chapter 10 Trigonometric Ratios
Exercise 10.1 | Q 36.2 | Page 26

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