Dan ABCD – rhombus, AC = 20cm; BD = 7cm. Find the area of a rhombus.

Given:
ABCD – rhombus,
AC = 20 centimeters;
BD = 7 centimeters.
Find the area of a rhombus, that is, S ABCD.

Decision:
Consider a rhombus ABCD. Its diagonals are AC and BD. The area of a rhombus is equal to the product of its diagonals and an ordinary fraction 1/2.
Therefore, the area of the rhombus ABCD is:
S ABCD = 1/2 * AC * BD;
S ABCD = 1/2 * 20 * 7;
S ABCD = (1 * 20 * 7) / 2;
S ABCD = (1 * 10 * 7) / 1;
S ABCD = 70/1;
S ABCD = 70 cm ^ 2.
Answer: 70 cm ^ 2.