Answer:
k = 18°
Explanation:
the upper right interior angle of the triangle and 81° are alternate angles and are congruent
upper right interior angle = 81°
since the 2 legs of the triangle are congruent then the triangle is isosceles with base angles being congruent , so
lower right interior angle = upper right interior angle = 81°
the sum of the 3 angles in the triangle = 180° , that is
k + 81° + 81° = 180°
k + 162° = 180° ( subtract 162° from both sides )
k = 18°