Question

Please explain the marked part of the sum (trigonometry ---> sums and products) given in the attachment. Please answer this fast. It's urgent. Tomorrow is exam. Please don't spam it.

Answer 1

Answer:

Step-by-step explanation:

Answer 2

HIII........{¶}

THERE IS YOUR ANSWER......{∆}

${ (\cos( \alpha ) - \cos( \beta ) ) }^{2} \\ \\ {4 \sin( \frac{ (\alpha + \beta) }{2} \sin( \frac{ \alpha - \beta }{2} ) ) }^{2} \\ \\ similiarly \\ \\ ( { \sin( \alpha ) - \sin( \beta )) }^{2} \\ \\ 4 {( \cos( \frac{ \alpha + \beta }{2} ) \sin( \frac{ \alpha - \beta }{ 2} ) )}^{2} \\ \\ now \: add \: and \: take \: 4{ \sin( \frac{ \alpha - \beta }{2} ) }^{2} \: \\ common \\ \\ 4 { \sin( \frac{ \alpha - \beta }{2} ) }^{2} ( { \cos( \frac{ \alpha + \beta }{2})}^{2} + { \sin( \frac{ \alpha + \beta }{2} ) }^{2} ) \\ \\ finally \: we \: got \\ \\ 4 { \sin( \frac{ \alpha - \beta}{2} ) }^{2}$

HOPE YOU LIKE IT THANK YOU.......{¶}