A = (1/2)·b·h
- A = Area = 28 yd2
- b = base = h-10
- h = height
A = (1/2)·b·h
28 = (1/2)(h-10)h
56 = h2 - 10h
0 = h2 - 10h - 56
0 = (h-14)(h+4)
h = 14 and -4. Since you can't have a negative height, h = 14 yd, The base is b = h-10 = 14 - 10 = 4 yd. Check:
A = (1/2)·b·h
28= (1/2)(4)(14)
28 = 28
Check!