Answer:
Step-by-step explanation:
From the diagram, quadrilateral BCEF is a cyclic quadrilateral.
Opposite angles if a cyclic quadrilateral sum up to 180°
The diagonals intersect at D to form two pairs of vertical angles, and vertical angles are congruent.
Also sum of angles in triangle CBD is 180°.
256 * 40 = 10,240 cm needed
so if the balls are 30 cm each then
10, 240 divided by 30 = 341.3
so the teacher will need 342 balls.