Question

triangle JKL is oblique with JK=20, KL=24, and angle K= 80 degrees. the areaof triangle JKL is?

Answer 1

find JL using cosine rule.
JL=sqrt( 20^2 + 24^2 - 2*20*24*cos80)

then calculate area using s,a,b,c
where s= (a+b+c)/2 where a,b,c are sides of the triangle
Area=sqrt[s *(s-a)*(s-b)*(s-c)]