Question

Hazel wrote the following statements to prove that c2 = x2 + y2.

1. Area of the grey four triangles inside figure A = A equals four times the quantity one-half times x times y, which equals 2 times x times y.

2. Area of the white square inside figure A = c2

3. Area of figure A = c2 + 2xy

4. Area of the four grey triangles inside figure B = A equals four times the quantity one-half times x times y, which equals 2 times x times y.

5. Area of the two white squares inside figure B = x2+ y2

6. Area of figure B = x2+ y2 + 2xy

7. Area of figure A = 2 × Area of Figure B, hence c2