1. The problem involves finding the unknown side length $x$ in right triangles using the Pythagorean theorem. 2. The Pythagorean theorem states that in a right triangle with legs $a$ and $b$ and hypotenuse $c$, the relationship is $$a^2 + b^2 = c^2$$ 3. Identify which side is the hypotenuse (the longest side) and which are the legs. 4. Substitute the known side lengths into the formula and solve for $x$. 5. If $x$ is a leg, rearrange the formula to $$x = \sqrt{c^2 - b^2}$$. 6. If $x$ is the hypotenuse, use $$x = \sqrt{a^2 + b^2}$$. 7. Always simplify under the square root and calculate the square root to find $x$. Example for (d): Given legs 1.3 km and $x$, hypotenuse 1.7 km. $$x = \sqrt{1.7^2 - 1.3^2} = \sqrt{2.89 - 1.69} = \sqrt{1.2} \approx 1.095$$ km Repeat this process for each triangle by identifying the hypotenuse and legs, then applying the Pythagorean theorem accordingly.