State if the three numbers can be the measures of the sides of a triangle. 1) 10,21,9
2) 6, 10, 7
3) 5, 7,2
4) 5,8,9

Step-by-step explanation:

sum of any two sides > third side.

difference of any two sides < third side.

1.10,21,9

10+9=19<21 (do not form a triangle)

2.

6,10,7

6+7=13>10

6+10=16>7

10+7=17>6

10-7=3<6

10-6=4<7

7-6=1<10

so it forms a triangle.

3.

5,7,2

5+2=7

(not a triangle)

4.

5,8,9

5+8=13>9

5+9=14>8

8+9=17>5

8-5=3<9

9-5=4<8

9-8=1<5

they form a triangle.