Answer:
AB = 45
Explanation:
If ΔABC is an isoceles triangle, then 2 sides are equal in length.
From the diagram, we can see that AC = BC (the dashes mean the sides are of equal length).
Therefore, equate AC and BC, then solve for x:
AC = BC
3x + 9 = 4x + 4
Subtract 3x from both sides: 9 = x + 4
Subtract 4 from both sides: 5 = x
So x = 5
Now we know that x = 5, we can substitute this into the expression for AB to find AB:
AB = 8x + 5
⇒ AB = (8 x 5) + 5
⇒ AB = 40 + 5
⇒ AB = 45