Respuesta :

I' wanting to say that you take 52 and subtract it from the 180, if u get the answer wrong I'm very sorry, have not done it in forever. 
 so my guess is 180-52= 128, hopefully this helps

The 2 red lines on the triangle mean that the 2 sides are equal.

Because the 2 sides are equal, Angle D is the same as angle C.

So now angle C & D are both 52 degrees, we can find Angle E

180 - 52 - 52 = 76 degrees

Angle DEF + Angle E need to equal 180 degrees

Angle DEF = 180 - 76 = 104 degrees