One angle in an obtuse isosceles triangle measures 40°. what are the measures of the other two angles?

"In an isosceles triangle two angles are the same and the third is different. However, the angles in the triangle must add up to 180. If the 100 degree angle was one of the 2 identical angles, then the angles in the triangle would add up to more than 200. Because of this the 100 degree angle must be the different angle."