A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself.
I believe the formula to find the height would be h= 2a/b and if you use that formula and plug in the area (21.7) of each triangle as well as the base (6) then you would get a height of 7.2 cm. I hope this is correct! :)