Question

Can anyone give step by step explanation for this as soon as possible...No negative answer pls...

Answer 1

a) sin(120°+$) +sin(120°-$)

= {sin120°cos$+cos120°sin$}+sin120°cos$-cos120°sin$

= 2sin120°cos$

= 2×sin(90+30) cos$

= 2×√3/2cos$

= √3cos$

b) cos(60+$) +cos(60-$)

= cos60cos$-sin60sin$}+cos60cos$+sin60sin$

=2cos60cos$

= 2×1/2cos$

= cos$