Question

verify cos(180 + x)= -cosx

Answer 1

\(\large\color{blue}{ \bf cos(180+x)=cos(180)cos(x)-sin(180)sin(x)=}\)

\(\large\color{purple}{ \bf cos(180)=-1}\)
\(\large\color{purple}{ \bf sin(180)=0}\)

\(\large\color{black}{ \bf hence,~~you~~get~}\)

\(\large\color{blue}{ \bf cos(180+x)=cos(180)cos(x)-sin(180)sin(x)}\)
\(\large\color{blue}{ \bf =(-1)cos(x)-(0)sin(x)=-cos(x)}\)