Answer:
A
Step-by-step explanation:
Since the triangle is right use Pythagoras' identity to find EF
The square on the hypotenuse is equal to the sum of the squares on the other two sides, that is
EF² + DF² = DE² ← substitute values
EF² + 12² = 18², that is
EF² + 144 = 324 ( subtract 144 from both sides )
EF² = 180 ( take the square root of both sides )
EF = → A
