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Mathematics

Assertion (A): If cosec (90° - 3A) = 1; angle A is 30°.

Reason (R):

cosec (90° - 3A) = 1
⇒ 90° - 3A = 90°
⇒ A = 0°

  1. A is true, R is false.
  2. A is false, R is true.
  3. Both A and R are true.
  4. Both A and R are false.

Trigonometric Identities

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Answer

A is false, R is true.

Explanation

Given, cosec (90° - 3A) = 1

⇒ cosec (90° - 3A) = cosec 90°

⇒ 90° - 3A = 90°

⇒ 3A = 90° - 90°

⇒ 3A = 0°

⇒ A = 0°3\dfrac{0°}{3}

⇒ A = 0°

According to Assertion, A = 30° (≠ 0°)

∴ Assertion (A) is false.

From the above calculation, cosec (90° - 3A) = 1

⇒ 90° - 3A = 90°

⇒ A = 0°

∴ Reason (R) is true.

Hence, Assertion (A) is false, Reason (R) is true.

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