Find the approximate length of segment ac.

Use the Pythagorean Theorem (a squared (a^2) + b squared (b^2) = c squared (c^2))
*a and b represent the legs (segments AB and BC)
*c is the hypotenuse (segment AC)

To find the lengths of the legs, count the squares.
AB=7 (a)
BC=4 (b)

Now plug in it:
7^2 + 4^2 = c^2
*When you square something, you multiply it by itself.*

7×7=49 and 4×4=16

49+16=65
This is c^2. To find c (the measure of segment AC), find the square root of 65 which is 8.06.

Let me know if you need more help.