In an isosceles triangle ABC, the angle B is 80 degrees. Find the other two corners of triangle ABC.

Consider an isosceles triangle ABC.
By condition, it is given that angle B or angle ABC is 80 degrees.
The base of this triangle is AC.
In order to find the values of the other two angles, recall the rule according to which the angles at the base are equal in an isosceles triangle.
So angle A is equal to angle C.
Now, according to the rule, the sum of the values of all the angles of the triangle is 180 °.
Next, we write ABC for a given triangle.
A + B + C = 180 °.
Since A = C, we write.
B + A + C = 180 °.
80 ° + 2A = 180 °.
2A = 180 ° – 80 °.
2A = 100 °.
A = 100 °: 2.
A = 50 °.
Answer: A = C = 50 °.