Answer:
100°
Step-by-step explanation:
AB = AC (given)
Therefore, ∆ ABC is an isosceles triangle.
m<B=m< C= 40°
sum of the interior angles of a triangle= 180°
m<A+40°+40°=180°
m<A = 180°-80° = 100°
< A is 100
<B is 40 <C is also 40
so 40+40= 80 then you have to do 180-80. Which equals 100.
