Correct. The architect can use the Pythagorean Theorem, $\displaystyle{{c}}^{{2}}={{a}}^{{2}}+{{b}}^{{2}}\usepackage{cmbright}\Huge\$ , to find the length of the walkway if he knows the length of the park along Arlington St and Davis St. These streets form the legs of the right triangle, and the walkway is the hypotenuse.