Answer:
the third option
Step-by-step explanation:
that is actually the proof for Pythagoras :
both squares have the total area of (a + b)².
each of the triangles (4 in figure 1, 4 in figure 2) has the same area as the others : a×b/2
so, for figure 1
(a + b)² = 4×a×b/2 + c² = 2×a×b + c²
and for figure 2
(a + b)² = 4×a×b/2 + a² + b² = 2×a×b + a² + b²
2×a×b + c² = 2×a×b + a² + b²
c² = a² + b²