Question

In ∆ abc,ab=bc,angle b=40°,then angle a is equal to

Answer 1

Answer:

$\large\bold\red{\angle A=70\degree}$

Step-by-step explanation:

Given,

A triangle ∆ABC.

Also,

AB = BC

Now,

°.° The two sides are equal ,

.°. It's an isosceles triangle.

Also,

It's Given that,

Angle B = 40°.

Now,

We know that,

Angles Opposite to Equal sides are equal.

Therefore,

We have,

=> Angle A = Angle C

Therefore,

We get,

From Angle sum properties of a triangle,

We know that,

=>Angles ( A + B + C ) = 180°

=> 40 + Angle A+ Angle C = 180

=> 2(Angle A) + 40 = 180

=> 2(Angle A) = 180 -40

=> 2(Angle A) = 140

=> Angle A = 140/2

=> Angle A = 70

Hnece,

Angle A is equals to 70°

Answer 2

Answer:

Step-by-step explanation:

Since AB = BC, So Angle A = Angle C.

b=40°

By A.S.P.

a + c = 140°

c + c = 140°

c = 70°