Question

Given the lengths of two sides of a triangle, find the range for the length of the third side. (Range means find between which two numbers the length of the third side must fall.) Write an inequality.
8 and 13

Answer 1

Answer:  5 < x < 21

Explanation:

Let x be the length of the third side. We can't find the exact value of x, as we don't have enough info, but we can find possible values for x.

The lower boundary for x is 13-8 = 5. It must be larger than this value.

At the same time, x must be smaller than 13+8 = 21 as well.

So x > 5 and x < 21 becomes 5 < x < 21

In short, x is between 5 and 21. It cannot equal either endpoint.