In rhombus ABCD, the height of AK crosses the diagonal BD at point E, ADE = 40 °. Find the value of the angle EAC.

Since the diagonal of the rhombus divides the angle at the apex in half, the angle ADC = 2 * ADE = 2 * 40 = 80.

The opposite angles of the rhombus are equal, then the angle ABC = 80. In the right-angled triangle ABK, the angle BAK = 180 – 90 – 80 = 10.

The sum of the adjacent angles of the rhombus is 180, then the angle BAD = 180 – 80 = 100, and the angle BAO = BAD / 2 = 100/2 = 50.

Then the angle EAC = BAO – BAE = 50 – 10 = 40.

Answer: The EAC angle is 40.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.