check the picture below
and isosceles triangle, has two equal sides, thus, sides "a" and "b" for the triangle to be an isosceles, have to be equal
See attached photo for answers. let me know if you are doing rounding to a specific decimal.

As we have to solve for b, it means we have to isolate b
So first of all subtract
from both sides
So we get

Now we need b , but its b^2 , so we can take square root on both sides.
taking square roots on both sides

Hence option B is correct
I do it when the numbers are to big but that's me
Answer:
B
Step-by-step explanation:
two sides are longer than the other two, D could also be one of the choices but rectangles have two parallel lines and have shorter sides at the sides