Can some explain what To do

AB = 5

Step-by-step explanation:

If the triangle is isosceles, then it has two equal sides, which must be facing the equal angles of the triangle (in our case the sides facing angles;  and  ) . That means that side AB equal side BC, then you can say:

Now, if x=3, then using the formula for side AB they gave you:

5 units.

Step-by-step explanation:

Because the triangle is isosceles the 2 sides opposite the equal angles are congruent.

AB = BC so:

3x - 4 = 5x - 10

10 - 4 = 5x - 3x

2x = 6

x = 3.

So the length of AB = 3(3) - 4 =  5 units.

30005

yes ok