It is not really a triangle but it is the only shape you may 3 sides of measure 4, 4, 8.
We have to examine first whether the figure enclosed by sides 4, 4 and 8 is an isoceles triangleor otherwise. The line segment measuring 8 units when divided in to 2 equal parts parts gives two line segments measuring 4 units on the same straight line. Hence:
The figure made by three line segment measuring 4, 4 and 8 units does not form a triangle but is athe same straight line. Line is defined as a locus of a point which has no measurement hence it does not have any area.
The figure determined by three line segments measuring 4, 4 and 8 is a straight line and NOT an isoceles triangle and does not have any area.