Bill draws a regular octagon. he divides the octagon into eight congruent isosceles triangles. what are the measures of the three angles in the isosceles triangle?

See the picture attached to better understand the problem

we know that
the formula for calculate the sum of the internal angles in a regular polygon is
Sum=(n-2)*180
for n=8
sum=(8-2)*180----> 1080°
1080°----> divide by number of sides
1080/8=135°
so
in the figure
∠ BAD=135°
∠ BAC=∠ BAD/2---> 135°/2---> 67.5°
∠ BAC=67.5°

the triangle ABC is an isosceles triangle
so
∠ ABC=∠ BAC
∠ ABC=67.5°
the sum of the internal angles of the triangle is equal to 180 degrees
∠ BCA=180-(67.5+67.5)------> 45°
∠ BCA=45°

the measures of the three angles in the isosceles triangle are
∠ BAC=67.5°
∠ ABC=67.5°
∠ BCA=45°