मराठी

In the following questions, two statements (i) and (ii) are given. Choose the valid statement. (i) If tan ⁡θ = 3/4, then cos ⁡θ = 3/5 (ii) If sin θ = 3 cos θ, then (sin θ – cos θ)/(sin θ + cos θ) - Mathematics

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प्रश्न

In the following questions, two statements (i) and (ii) are given. Choose the valid statement.

(i) If `tan θ = 3/4`, then `cos θ = 3/5`

(ii) If sin θ = 3 cos θ, then `(sin θ - cos θ)/(sin θ + cos θ) = 1/2`

पर्याय

  • Only (i)

  • Only (ii)

  • Both (i) and (ii)

  • Neither (i) nor (ii)

MCQ
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उत्तर

Only (ii)

Explanation:

(i) False. `tan θ = "Opposite"/"Adjacent"`

= `3/4` 

So, the triangle sides are 3, 4, 5.

Therefore, `cos θ = "Adjacent"/"Hypotenuse"`

= `4/5`, not `3/5`

(ii) True. If sin θ = 3 cos θ, write sin θ = 3c and cos θ = c (c ≠ 0).

Then `(sin θ - cos θ)/(sin θ + cos θ)`

= `(3c - c)/(3c + c)`

= `(2c)/(4c)`   ...(Sign of c cancels)

= `1/2`

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पाठ 17: Trigonometric Ratios - Exercise 17B [पृष्ठ ३६३]

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नूतन Mathematics [English] Class 9 ICSE
पाठ 17 Trigonometric Ratios
Exercise 17B | Q 4. | पृष्ठ ३६३
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