Question

In ΔABC, if BC = AB and ∠B=80° then find the measure of 1/2∠A.

Answer 1

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$\sf{solution}$

▪️Given that in triangle ABC, BC = AB which means ABC is an isosceles triangle.

▪️We know the sum of angles in a triangle is 180°.

▪️Since it is an isosceles triangle the measure of two angles will be same.

▪️ Let ∠A = x and ∠c = x

▪️We know,

▪️Sum of all angles = 180°

▪️x+x+80° = 180°

▪️2x= 180°-80°

▪️2x=100°

▪️x=

$\frac{100}{2}$

 ▪️= 50

▪️Thus the measure of ∠A = 50°

Answer 2

Step-by-step explanation:

∆ABC

if BC=AB

SO <A=<C

<A+<B+<C=180°

OR,<A+<C=100° [<B=80°

OR,2<A=100° [<A=<C

OR,<A=50°

OR,1/2<A=25°