AB and CD are perpendicular to plane B (betta). AB = 9 cm, CD = 6 cm. Find AC.

Perpendicularity means that the angle between the two lines is 90 degrees, which is a right angle. This means that the triangle obtained by the perpendiculars AB and CD is rectangular. To solve the problem, we can apply the Pythagorean theorem: the sum of the squares of the legs of a rectangular slummer is equal to the square of the hypotenuse of the triangle.
AB = 9, CD = 6.
AC ^ 2 = AB ^ 2 + CD ^ 2 = 9 ^ 2 + 6 ^ 2 = 81 + 36 = 117
AC = root of 117, that is approximately 10.82 cm.
Answer: 10.82 cm