Answer:
A
Explanation:
The median AB bisects DC at right angles ,hence BD = 4
Using Pythagoras' identity on the right triangle ABD
The square on the hypotenuse AD is equal to the sum of the squares on the other 2 sides, that is
AB² + BD² = AD², that is
AB² + 4² = 5²
AB² + 16 = 25 ( subtract 16 from both sides )
AB² = 9 ( take the square root of both sides )
AB =
= 3 feet → A