Respuesta :

ghanami

Answer:

h= 7/6 mm

Step-by-step explanation:

hello :

the area is :  A= (b+B)×h/2

calculate h the height  : 2A = (b+B)×h

so:  h = 2A/(b+B)

you have : A=21/5   and  b= 3    and B= 21/5

h= 2(21/5)/(3+21/5)

h= (42/5) /(36/5)

h= 42/36

h= 7/6 mm