Evaluate the following: sin 36° cos 9° + cos 36° sin 9° - Mathematics

Short Note

Evaluate the following:
sin 36° cos 9° + cos 36° sin 9°

Solution

$\sin36^\circ\cos9^\circ + \cos 36^\circ \sin9^\circ$
$= \sin\left( 36^\circ + 9^\circ \right) \left[\text{ Using }\sin A \cos B + \cos A \sin B = \sin\left( A + B \right) \right]$
$= \sin45^\circ = \frac{1}{\sqrt{2}}$

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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 7.3 | Page 19