Given an isosceles trapezoid ABCD, with a large base (AD), find AC + BD if BD = 10 cm.

1. The property of an isosceles trapezoid is known: the lengths of the diagonals of such a trapezoid are equal.

2 By the condition of the problem in an isosceles trapezoid ABCD BD is one diagonal, the length of which is 10 centimeters.

This means that the other diagonal AC, according to the property of the diagonals of an isosceles trapezoid, is equal to the diagonal BD and is also equal to 10 centimeters.

Find the sum of the diagonals

AC + BD = 10 cm + 10 cm = 20 centimeters.

Answer: The sum of the AC + BD diagonals is 20 centimeters