See the attached picture:
Answer:
540
Step-by-step explanation:
I honestly put it in my calculator and squared it,
291600
/ \
540 540
you have a pair, you don't have to do anything else, and you're done
It should be 10...because the 2 angles in the base are the same so the length is mirrored
right 3 units down 5 units

right 3 units = (3,0)
down 5 units = (0,-5)
vertex = (h,k) therefore.

Then convert the vertex form into standard form for the equation in the choice.

Thus, the answer is B.