If the base is AB = 12 cm and the height of AB is h = 7 cm the area is:
If the base is BC = 8 cm and the area didn't change you'll get the height by:
To the second question:
1. The given length must be the legs of the right triangle (not the hypotenuse!)
2. The area of this triangle is With your values you get:
3. The volume of a prism is calculated by:
Plug in the values you know to get the volume.
The following question must be wrong: A mass of metall measured in cm is a mess.