Cho hình vẽ sau và chứng minh: ME // NF và tìm x

The missing value, x, can be found using the properties of similar triangles.

First, we can see that triangle MNE is similar to triangle FNC. This means that the corresponding sides of these triangles are proportional.

Using this information, we can set up the following proportion:

MN/FC = NE/NF

Substituting the given values, we have:

120/60 = x/90

Simplifying this proportion, we get:

2 = x/90

To solve for x, we can cross multiply:

2 * 90 = x

x = 180

Therefore, the missing value, x, is 180.