Answer:
m∠ACD = 130
Step-by-step explanation:
If ABC is an isosceles, AB = AC and m∠A = 80°, then m∠B and m∠C is equal to 50°.
This is because angles in a triangle adds up to 180°.
180° - 80° = 100°/2 = 50°
∴ m∠ACD = 130°, this is because the interior opposite angles in a triangle is supplementary to the opposite exterior angle:
50° + 80° = 130°
Or
Angles on a straight line adds up to 180°.
180° - 50° = 130°
