My answer would be: Tim is incorrect, because more than one triangle can be drawn with the given information.
Given:
Isosceles triangle and has a 70° angle.
An isosceles triangle is a triangle that has 2 congruent angle. Since all interior angle must have a sum of 180°, the possible angles of an isosceles triangle with a 70° angle are:
1) 180° - 70° = 110°
110° / 2 = 55°
Angles are 70°-55°-55°
2) 180° - 70° = 110°
110° - 70° = 40°
Angles are 70°-70°-40°
The given information can create 2 isosceles triangle. Thus, Tim is wrong in his claims.
