Which angles are right?

A. angle KLJ

B. angle MLK

D. angle EFH

All three angles mentioned have a tiny square marker to visually show the reader that the angle is a right angle, aka 90 degree angle. We can say that the segments forming the angle are perpendicular segments.

For angle GFE, it is smaller than angle EFH because point G is between or inside the angle EFH. So there is no way that angle GFE is a right angle.

0.02040816326

6mm^3 or .6cm^3

      216

      /   \

  36     6

  /   \     /

6     6   6

factor trees are nice.