M22-02

Official Solution:


If the diagonals of rectangle \(ABCD\) intersect at point \(E\), what is the degree measure of \(\angle AEB\) ?



(1) The degree measure of \(\angle EDC\) is 15º.

When two parallel lines are cut by a transversal, alternate interior angles are equal. Therefore, angles EDC and ABE are equal since AB and DC are parallel and intersected by DB. Thus, we know that angle EDC is 15 degrees.

Next, since ABCD is a rectangle, its diagonals bisect each other, meaning that AE = BE. Thus, angle ABE = angle BAE = 15 degrees.

Finally, in triangle ABE, we know that angles ABE, BAE, and AEB add up to 180 degrees. Since ABE and BAE are both 15 degrees, we can solve for AEB to be 150 degrees.

Therefore, the first statement is sufficient.

(2) The degree measure of \(\angle ACB\) is 75º.

Since ABC is a right triangle, we know that angle ACB and angle BAC add up to 90 degrees. Therefore, angle BAC is 15 degrees. Finally, in triangle ABE, we know that angles ABE, BAE, and AEB add up to 180 degrees. Since ABE and BAE are both 15 degrees, we can solve for AEB to be 150 degrees.

Therefore, the second statement is sufficient.


Answer: D