Pls . this is the photo from my last question

E 10 sqrt(2)

Step-by-step explanation:

If this is an isosceles triangle than AB = BC  and AB = 10  so BC = 10

We want to us the Pythagorean theorem since it is a right triangle

a^2 + b^2 = c^2 where a and b are the legs and c is the hypotenuse

10^2 + 10^2 = AC^2

100 + 100 = AC^2

200 = AC ^2

Take the square root of each side

sqrt(200) = sqrt( AC^2)

sqrt(100*2) = AC

We know sqrt(ab) = sqrt(a) sqrt(b)

sqrt(100) sqrt(2) = AC

10 sqrt(2) = AC