Answer:
See below in bold.
Its the second choice.
Explanation:
The sides b and d are the legs of a 30-60-90 triangle so the sides are in the ratio 2 : 1 :√3 where 2 = the hypotenuse.
Here the hypotenuse = 10. Therefore:
10 = 2*5, so d = 1/2 * 10 and b = √3*5.
d = 5 , b = 5√3.
Now a , b and c are also the sides of a 30-60-90 triangle and we know that b = 5√3.
So a ( the hypotenuse = 2 * 5√3 = 10√3.
and c ( the longest leg) = 5√3 * √3 = 15.