Question

n triangle ABC, if AB=BC and ∠B = 70 then find the ∠ A​

Answer 1

Answer:

55°

Step-by-step explanation:

Since AB = BC,

triangle ABC is an isosceles triangle

Therefore, base angles i.e. angle A and angle C will be equal

angle A = angle C

Therefore, applying the sum of all angles of a triangle theorem,

angle A + angle B + angle C = 180°

since, A = C

2A + C = 180°

2A + 70° = 180°

2A = 180° - 70°

2A = 110°

A = 110° ÷ 2

A = 55°

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Answer 2

Step-by-step explanation:

as the question said the angle B is equal to 70° .

so , according to the question the triangle is equal to 180° .

let angle A and angle C be x .

so , if we add angle A , angle B and angle C the sum will 180 ° .

as solving the equation the answer will be 110°.

<A + <B + <C = 180°

<A +70° +<C = 180°

X + 70° +x = 180°

2x +70° = 180°

2x = 180° -70°

2x = 110°

and on diving it by two

as angle A and angle C is equal to 2x .

and the final answer will 55°

2x = 110°

x = 110° ÷ 2

x = 55°