मराठी

If seс (90° − 3A) . cos 48° = 1 and 0 ≤ 3A ≤ 90°; find the value of angle A.

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प्रश्न

If seс (90° − 3A) . cos 48° = 1 and 0 ≤ 3A ≤ 90°; find the value of angle A.

बेरीज
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उत्तर

Given:

seс (90° − 3A) . cos 48° = 1 and 0 ≤ 3A ≤ 90°

Formula:

\[\sec(\theta) = \frac{1}{\cos(\theta)} \text{ and } \sec(90^\circ - \theta) = \csc(\theta)\]

Solution:

\[\sec(90^\circ - 3A) = \frac{1}{\cos 48^\circ}\]  [Transposing cos 48° to the right side]

seс (90° − 3A) = sec 48°  [Using the reciprocal identity \[\frac{1}{\cos 48^\circ} = \sec 48^\circ\]]

90° − 3A = 48°  [Equating the angles of equal secant functions]

3A = 90° − 48°  [Rearranging terms to solve for 3A]

3A = 42°  [Subtracting 48° from 90°]

\[A = \frac{42^\circ}{3}\]  [Dividing both sides by 3]

A = 14°  [Simplifying the division]

∴ A = 14°

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पाठ 21: Trigonometrical Ratios [Sine, Consine, Tangent of an Angle and their Reciprocals] - TEST YOURSELF [पृष्ठ ३३५]

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सेलिना Concise Mathematics [English] Class 9 ICSE
पाठ 21 Trigonometrical Ratios [Sine, Consine, Tangent of an Angle and their Reciprocals]
TEST YOURSELF | Q 10. | पृष्ठ ३३५
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