To determine the length of the other leg \( b \) in a right triangle where \( a = 7.2 \) is one leg and \( c = 11.1 \) is the hypotenuse, we can use the Pythagorean theorem, which states:
\[ c^2 = a^2 + b^2 \]
We can rearrange this formula to solve for \( b^2 \):
\[ b^2 = c^2 - a^2 \]
Now we can plug in the values for \( a \) and \( c \):
\[ b^2 = (11.1)^2 - (7.2)^2 \]
Calculating \( (11.1)^2 \):
\[ (11.1)^2 = 123.21 \]
Now calculating \( (7.2)^2 \):
\[ (7.2)^2 = 51.84 \]
Now we substitute these values back into our equation for \( b^2 \):
\[ b^2 = 123.21 - 51.84 = 71.37 \]
Now we take the square root of both sides to find \( b \):
\[ b = \sqrt{71.37} \]
Calculating the square root:
\[ b \approx 8.4 \]
So, to the nearest tenth, the length of the other leg \( b \) is:
\[ \boxed{8.4} \]
Now, regarding the question of whether the forces in the pair are pulling at right angles to each other: since we have established that \( a \) and \( b \) are the legs of a right triangle and \( c \) is the hypotenuse, it follows that the forces represented by \( a \) and \( b \) are indeed acting at right angles to each other.