Two of the sides of an isosceles triangle measure 17cm and 8cm.

**How tall is the third side?**

#### Solution

If it is an isosceles triangle, the missing side has to measure the same as one of those we already know. As two sides of 8cm and one of 17cm cannot form a triangle since the length of the sum of the two small sides would not reach to join with the greater side, the answer is **17cm**.