Answer:
AC = [tex]\sqrt{AB^2 + BC^2}[/tex]
Step-by-step explanation:
Here we have to draw the figure.
When the rectangle is folded A to C. we get a right triangle.
Here we have to use the Pythagorean theorem to find the side lenght of B.
The sides length of B is AC.
By the Pythagorean theorem, the sum of the squares of the sides is equal to the square of the hypotenuse.
Therefore,
AC^2 = AB^2 + BC^2
Taking the square roots on both sides, we get
AC = [tex]\sqrt{AB^2 + BC^2}[/tex]