These triangles are similar. find the missing length, h.
7*6*7/2. 1*h*1/2

If I understand the question correctly, the sides of one triangle
are 7...6...and 7/2, and the sides of the second triangle
are 1...h...and 1/2 , and the triangles are similar.

OK. The ratio of the first pair of sides is 7 / 1 = 7, and the
ratio of the second pair of sides is (7/2) / (1/2) = 7, so
I'm pretty sure the ratio of the missing pair of sides is also 7 .

h = 6/7

Iwould think that the correct answer is 8.1