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Evaluate the Following Cos 60° Cos 45° - Sin 60° ∙ Sin 45° - Mathematics

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Question

Evaluate the following

cos 60° cos 45° - sin 60° ∙ sin 45°

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Solution

cos 60° cos 45° - sin 60° ∙ sin 45° …(i)

By trigonometric ratios we know that,

`cos 60^@ = 1/2 cos 45^@ = 1/sqrt2`

`sin 60^@ = sqrt3/2    sin 45^@ = 1/sqrt2`

By substituting above value in (i), we get

`1/2. 1/sqrt2 - sqrt3/2. 1/sqrt2 => (1 - sqrt3)/(2sqrt2)`

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Chapter 10: Trigonometric Ratios - Exercise 10.2 [Page 41]

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RD Sharma Mathematics [English] Class 10
Chapter 10 Trigonometric Ratios
Exercise 10.2 | Q 3 | Page 41

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