Yo sup??
we have to apply trigonometry here.
To find DE we have to find the sine of the angle EDC
sin42=DC/DE
=6/DE
DE=6/sin42
If you have a calculator then u can find the value of sin42 directly or else u can take sin42=sin45( approx)=1/√2=0.707
DE=6/0.707
DE=8.9 (approx)
Hope this helps.