Mathematics
Δ ABC is an isosceles triangle in which AB = AC. Side BA is produced to D such that AD = AB. Show that ∠BCD is a right angle.

Related Questions
ABC is a triangle in which altitudes BE and CF to sides AC and AB are equal. Show that
(i) Δ ABE ≅ Δ ACF
(ii) AB = AC, i.e., ABC is an isosceles triangle

ABC and DBC are two isosceles triangles on the same base BC. Show that ∠ABD = ∠ACD.

ABC is a right angled triangle in which ∠A = 90° and AB = AC. Find ∠B and ∠C.
Show that the angles of an equilateral triangle are 60° each.