Can the sides of a triangle have lengths 2,6, 9?

No

Step-by-step explanation:

Using the Pythagorean theorem,  a squared + b squared = c squared, where c is the hypotenuse. 2 squared is 4, 6 squared is 36. 4+36 is 40, but 9's square is 81. This means that it can't be a triangle.

Hope this helps :)

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.

i believe it's a.

i'm not sure on this one, most likely correct.