In the given isosceles triangle ABC, AB = AC, ∠ABC = 70°. Find ∠ BAC.
40∘
Since ABC is an isosceles triangle, two sides of the triangle will be equal.
From the question, AB = AC
Hence, the base angles will be equal.
⇒ ∠ABC = ∠ACB = 70∘
∠BAC + ∠ABC + ∠ACB = 180∘ ( Angle sum property of a triangle)
⇒∠BAC+70°+70°=180°
⇒∠BAC = 180∘ - 70∘ - 70∘
⇒∠BAC = 180∘ - 140∘
⇒∠BAC = 40∘
Hence, the value of ∠BAC = 40°.