Question 1150871
As a start,  the missing angle opposite the 400 cm side is  {{{180-60-50=70}}} degrees.


Law of sines should give equations  {{{L/sin(50)=400/sin(70)}}} and {{{R/sin(60)=400/sin(70)}}}.   That is taking L is opposite of the 50 degree angle,...


L is opposite the 50 degree angle and R is opposite the 60 degree angle.
{{{system(L=326.08,R=368.64)}}}


y, for height
{{{y/L=sin(60)}}}
{{{y=326.08*sin(60)}}}
{{{y=282.3935}}}{{{approximately}}}


AREA,
{{{(1/2)*400*282.3935}}}
Round the result as needed.