Answer: 0.04 inches²
Step-by-step explanation:A of Triangle = 1/2*B*H where B is base and H is height. Find the area of the bigger triangle and then subtract the area of the smaller triangle
1/2*(0.4)*(0.3) = 0.06
1/2*(0.4)*(0.1) = 0.02
0.06 - 0.02 = 0.04