Respuesta :

Kimchicaik
Well. The formula for the area of a trapezoid is b1 + b2 over 2 times h. 

a = b1 + b2 (h)
--------------------
           2

3.9 = 4+2.5 (h)
--------------------
           2

3.9 = 6.5(h)
         ----
         2

height = 1.2 cm.