The diagonal AC is drawn in the rectangle ABCD. The BAC angle is 30 degrees. What are the angles of the ACD triangle?

The diagonal AC divides a rectangle into two right-angled triangles. Therefore, we can immediately say that in the triangle ACD the angle ACD is straight, that is, <ACD = 90 degrees. The diagonal AC divided <BAD into angles <BAC and <CAD. The BAC angle is 30 degrees and the BAD angle is 90 degrees by convention. Then we find what <CAD is equal to:

90 – 30 = 60 (degrees).

The angles in a right triangle add up to 180 degrees. Let’s calculate the last unknown side in the triangle ACD:

180 – (90 + 60) = 30 (degrees).