Question

40° 4.In ΔΑΒC, BC=AB and ZB= 80° , then ZA is equal to :​

Answer 1

BC=AB

$\bf\implies \: ∠A=∠C (As \: angles \: opposite \: to \: equal \: side \: are \: equal)$

let thte angles be x each.

Now by angle sum property

$\mapsto \: \angle \: A+∠B+∠C=180 \degree$

$\implies \: x+80+x=180$

$\implies \: 2x=180−80$

$\mapsto \: 2x=100$

$\mapsto \: x = 50$

$\bf \: ∠A=50 \degree$