Which three lengths could be the lengths of the sides of a triangle?

Option D is correct.

Step-by-step explanation:

We use the following result:

If sum of two sides of a triangle is greater than third side then Triangle is possible with those sides.

Option A).

a = 21 , b = 7 , c = 7

a + b = 21 + 7 = 28 > c

b + c = 7 + 7 = 14 < a

So, These length cannot be lengths of the sides of the triangle.

Option B).

a = 20 , b = 6 , c = 8

a + b = 20 + 6 = 26 > c

b + c = 6 + 8 = 14 < a

So, These length cannot be lengths of the sides of the triangle.

Option C).

a = 15 , b = 5 , c = 20

a + b = 15 + 5 = 20 = c

So, These length cannot be lengths of the sides of the triangle.

Option D).

a = 9 , b = 14 , c = 22

a + b = 9 + 14 = 23 > c

b + c = 14 + 22 = 36 > a

a + c = 9 + 22 = 31 > b

So, These length can be lengths of the sides of the triangle.

Therefore, Option D is correct.

line or a linear equation graph

step-by-step explanation: