Find the area of triangle JKL below.

This is a  30-60-90 right  triangle

The hypotenuse  = 20

One of the legs  =  20 / 2  =  10

And the other  leg  = 10√3

The area  = (1/2) (product of the legs )   = (1/2) (10) ( 10√3)  =  50√3   units^2