Tell whether the side lengths 3,9, and 15 form a triangle.

No, because 9 + 3 isn’t greater than 15.

Explanation:

According to the triangle inequality theorem, the sun of the 2 shorter legs of a triangle must add up and be greater than the longest side of the triangle which is the hypotenuse.

Therefore, in this case, the addition of 3 and 9 which is 12 is less than 15, therefore, the side lengths doesn't make a triangle.

just took the test the answer is b.