Question

plz solve this question​

Answer 1

$\frac{sin \: a \: + sin \: b}{2} \leqslant \sin( \frac{a + b}{2} ) \\ sin \: ( \frac{a + b}{2} )cos( \frac{a - b}{2} ) \leqslant \sin( \frac{a + b}{2} ) \\ cos( \frac{a - b}{2} ) \leqslant 1 \\ value \: of \: cos \: cannot \: be \: greater \: than \: 1 \: hence \: proved \\ mark \: it \: bainliest$