Answer:
This is kinda hard to answer, but i'm going to say the answer might be 14 cm squared.
Explanation:
I don't have much info, but I can say that the 7 cm side can be split into 2 lengths of 5 cm, and 2 cm.
Using this i can do 5 times 4 to get 20, but sense it's a triangle, the triangle would be half of a square making it 10 cm for the left part of the triangle.
Using the knowledge of the left triangle, I can do 2 times 4, which equals 8, half of 8 cm is 4 cm, and now i can do the equation of 10 cm plus 4 cm equals the answer of 14 cm squared.