Draw a circle with its two chords AB and CD such that AB is not parallel to CD. Draw the perpendicular bisector of AB and CD. At what point do they intersect each other.
The perimeter of a quadrilateral is 40cm. If the first three sides of a quadrilateral, taken in order are 13cm,10cm, and 12cm respectively, and the angle between fourth side and the third side is a right angle, find the area of the quadrilateral.
A box contains 4 green and 6 orange balls. Max takes out a ball, puts it back, and then takes out another ball. What is the probability that both balls were green?