Using a=12bh what is an equation to represent the area of a triangle?

When you answer this can you explain

Find the number of liters in 12.8 gal of gasoline. round to the nearest hundredths

Use the formulas a = x 2 – y 2, b = 2xy, c = x 2 + y 2 to answer this question. one leg of a right triangle has length 11 and all sides are whole numbers. find the lengths of the other two sides. the other leg = a0 and the hypotenuse = a1