#9. There are 180 degrees in a triangle. We already know two of the sides which added together make 112. Then we do, 180-112=68
#10. We do the same process. 90 + 60 = 150 150-180= 30
#11. To find whether or not any three numbers can make a triangle, two of the numbers must equal more than the remaining number. But this has to be the case for any combination. 6+7=13. 13 is larger than 11. So yes it can.
#12. 8+2=10 which may be bigger than 6 but, 6+2=8. Which is equal to 8. So no, it cannot make a triangle.
