Question

5. In triangle ABC, if AB = BC and triangle B = 100°, then triangle C is equal to.
(a) 40°
(b) 50°
(c) 120°
(d) 80°
please answer in formula​

Answer 1

Answer:

40°

Step-by-step explanation:

As sum of triangle is 180°

A+B+C=180°

A+100+C=180

A+C=180-100

A+C=80

A=40

C=40

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Answer 2

OPTION A = 40°

EXPLANATION:

According to the question,

Δ ABC, AB = AC and ∠B = 100°

Since, BC = AB

Since, BC = ABΔ ABC is an isosceles triangle.

Since, BC = ABΔ ABC is an isosceles triangle.Let, ∠C = ∠A = x

Since, BC = ABΔ ABC is an isosceles triangle.Let, ∠C = ∠A = x∠B = 100° (Given)

We know that,

Using angle sum property,

Sum of interior angles of a triangle should be = 180°

∠A + ∠B + ∠C = 180°

⇒ x + 100° + x = 180°

⇒ 2x = 180° – 100°

⇒ 2x = 80°

⇒ x = 40°

Therefore, ∠C = ∠A = 40°