Find the angles of an isosceles triangle if the angle at the base is 4 times the angle between the sides.

Let the angle between the sides be x, then the angle at the base is 4x. In an isosceles triangle, the two angles adjacent to the base are equal. The angles of a triangle add up to 180 degrees.
Let’s make the equation:
x + 4x + 4x = 180;
9x = 180;
x = 180/9 = 20 degrees.
Therefore, the angle between the sides is 20 degrees, the angles at the base of the triangle are 20 x 4 = 80 degrees.