The formula for the area of a triangle is 1/2 * base * height.
Since the base is 42 yards and the area is 672 square yards, we have:
Area = 1/2 * base * height
672 = 1/2 * 42 * height
height = (672 * 2) / 42
height = 32 yards
Hence, the height is 32 yards.