According to the triangle similarity: x/6 = 3/(3+4), x= 18/7.
The base (top) of the triangle in the shadow (1) = 6- 18/7=24/7.
Shadow (1) Triangle area = 1/2*24/7*4 = 48/7.
Shadow (2) Triangle area = 1/2* 18/7*3 = 27/7.
48/7-27/7 = 2 1/7 = 3
In the figure, the shaded triangle area of ① is 3 square centimeters larger than ②.