Explanation:
the area of a triangle is baseline×height/2
in case of such a right-angled triangle we can use the sides that enclose the 90 degree angle as baseline and height.
so,
B = 8×6/2 = 8×3 = 24 yd²
the height h is 8 yd (as the picture clearly shows).
the perimeter of the base is the sum of all three sides
P = 8 + 6 + 10 = 24 yd