It cannot create a triangle because the two shorter sides, of length 2 and 3, added up is equivalent to the longest side. This means that it would not be a triangle, just 2 overlapping lines. Try drawing a triangle with these side lengths and you will see what I mean.
A= 3400t + 600 | given formula 21000= 3400t + 600 | substitute the altitude into the formula 20400 = 3400 | subtract 600 from both sides 6 = t | divide both sides by 3400 6 minutes
