Answer:
Answer E is correct
Step-by-step explanation:
Let the Length of EF be x
Use PYTHAGORAS theorem to find the length of EF
EF² + DF² = DE²
[tex] {x}^{2} + {10}^{2} = {20}^{2} \\ {x}^{2} + 100 = 400 \\ {x}^{2} = 400 - 100 \\ {x}^{2} = 300 \\ x = \sqrt{300} [/tex]
So,
[tex]EF = \sqrt{300} [/tex]
Hope this helps you.
Let me know if you have any other questions :-)
