The internal angles of an equilateral triangle all measure how many degrees?

60

How many dimensions does a semicircle feature?
Is it 2?

In an equilateral triangle, all angles are equal. That means, each one is 180/3=60. Correct.

A semicircle is indeed a two-dimensional figure.

Yes, a semicircle is a two-dimensional geometric shape. It is formed by taking half of a circle, which is a two-dimensional shape, so it also remains two-dimensional. It is important to note that the term "dimension" refers to the number of coordinates needed to locate a point in space. In the case of a semicircle, two coordinates (x and y) are sufficient to describe any point on it.