Question

Q-1: In ∆ABC, BC = AB and ∠B = 80°. Then ∠A is equal to:

80 degree

40 degree

50 degree

100 degree

​

Answer 1

Answer:

BC=AB

⇒∠A=∠C (As angles opposite to equal side are equal)

let thte angles be x each.

Now by angle sum property

∠A+∠B+∠C=180

∘

⇒x+80

∘

+x=180

∘

⇒2x=180

∘

−80

∘

⇒2x=100

∘

⇒x=50

∘

∴∠A=50

option c is the right answer.

Answer 2

Answer:

80°

Step-by-step explanation:

AB=BC

angle B=angleA

( angle opposite to equal sides are always equal)

angle B=80°

so,

angle A=80°