Question

In triangle ABC,BC=AB and angle B=80.What is the value of angle A *​

Answer 1

Answer:

50

Step-by-step explanation:

Bc=AB means it is isosceles triangle

then 2x+80=180

2x=100

X=50

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Answer 2

Answer:

Refer to the triangle diagram.

If BC = AB (given)

then, ΔABC is an isosceles triangle,

therefore, ∠ A = ∠ C --------------- 1

and, ∠B = 80° (given) ---------------2

We also know,

∠ A + ∠B + ∠ C = 180° [Angle-Sum Property of A Triangle]

∴ ∠ A + 80° + ∠ C = 180° [See eq.2]

⇒ 2∠A + 80° = 180° [A=C; See eq.1]

⇒ 2∠A = 100°

⇒ ∠A = 50°

therefore, the value of angle A is 50 degrees