Answer:
Step-by-step explanation:
it's 2ab + c^ 2
why?, well, we can change the position of the 2 triangle in each corners into this (in the picture below) :
you can see that a^2 + b^2 = c^2
then there are 2 ab from 4 triangles we add that create 2 rectangle then we multiply each rectangles by its sides
so , c^ 2+ 2ab is the answer
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hope this is helpul!