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Evaluate the Following: Cos 47° Cos 13° − Sin 47° Sin 13° - Mathematics

Short Note

Evaluate the following:
cos 47° cos 13° − sin 47° sin 13°

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Solution

\[ \cos47^\circ\cos13^\circ - \sin47^\circ \sin13^\circ\]
\[ = \cos\left( 47^\circ + 13^\circ \right) \left[\text{ Using }\cos A \cos B - \sin A \sin B = \cos\left( A + B \right) \right]\]
\[ = cos 60^\circ = \frac{1}{2}\]

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APPEARS IN

RD Sharma Class 11 Mathematics Textbook
Chapter 7 Values of Trigonometric function at sum or difference of angles
Exercise 7.1 | Q 7.2 | Page 19
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