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If sin x = cos x and x is acute, state the value of x

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Question

If sin x = cos x and x is acute, state the value of x

Sum
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Solution

The angle, x is acute and hence we have, 0 < x
We know that
cos2x + sin2 x = 1
⇒ 2sin2 x = 1

⇒ sin x = `(1)/(sqrt2)`

⇒ x = 45°

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Chapter 21: Trigonometrical Ratios [Sine, Consine, Tangent of an Angle and their Reciprocals] - EXERCISE 21 (C) [Page 322]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 21 Trigonometrical Ratios [Sine, Consine, Tangent of an Angle and their Reciprocals]
EXERCISE 21 (C) | Q 8. (i) | Page 322
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