Please please help please

AB = BC = 4

Step-by-step explanation:

This is a 45-45-90 triangle (right isosceles). This means that the side ratio is

1:1:, where AC is sqrt 2, and AB and BC are 1. Now, we need to plug this into our ratio. If sqrt 2 is 8, then 1 is x.

8/ = x/1 = x

x = 8/ = 4 (rationalized)

AB and BC are both 4 * sqrt 2

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: