Question

sin pi/10+sin13pi/10 value=​

Answer 1

$= \sin( \frac{\pi}{10} ) + \sin( \frac{13\pi}{10} ) \\ \\ = \sin(18) + \sin( \frac{10\pi + 3\pi}{10} ) \\ \\ = \sin(18) + \sin(\pi + \frac{3\pi}{10} ) \\ \\ = \sin(18) - \sin( \frac{3\pi}{10} ) \\ \\ = \sin(18) - \sin(54) \\ \\ = \sin(18) - \sin(90 - 36) \\ \\ = \sin(18) - \cos(36) \\ \\ = \frac{ \sqrt{5} - 1 }{4} - \frac{ \sqrt{5} + 1}{4} \\ \\ = \frac{ \sqrt{5} }{4} - \frac{1}{4} - \frac{ \sqrt{5} }{4} - \frac{1}{4} \\ \\ = - \frac{2}{4} \\ \\ \bold \green{ = - \frac{1}{2} } \: \: \boxed{ \bold \red{ans....}}$

till then be happy..........