In triangle ABC it is known that AB = BC, angle ABC = 104 degrees. Find angle BCA.

Since AB = BC, triangle ABC is isosceles.
This means that the two angles BAC and BCA at the base are equal.
The sum of all the angles of the triangle is 180 degrees.
Hence, the angles BAC and BCA = X.
104 + X + X = 180;
2X = 180-104;
2X = 76;
X = 38.
Answer: BCA angle = 38 degrees.

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