9. The sum of two sides must be greater than the third side. It can't be 5 because [tex]5+5=10\not>12[/tex]. It can't be 7 because [tex]5+7=12\not>12[/tex]. It can't be 17 because [tex]5+12=17\not>17[/tex]. So it's 12.
10. a. Turk, McAllister b. Market, Mission, Howard c. not sure about this one