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Prove that: cos2 30° - sin2 30° = cos 60° - Mathematics

Question

Prove that:

cos² 30° - sin² 30° = cos 60°

Sum

Solution

`(sqrt3/2)^2 - (1/2)^2 = 3/4 - 1/4 = 2/4 = 1/2 = cos60°`

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Chapter 23: Trigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios] - Exercise 23 (A) [Page 291]

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Selina Concise Mathematics [English] Class 9 ICSE

Chapter 23 Trigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios]
Exercise 23 (A) | Q 3.4 | Page 291