In triangle ABC, bisector of angle BAC meets opposite side BC at point D. If BD = CD, prove that △ ABC is isosceles.

In Δ ABC, D is a point on BC such that AB = AD = BD = DC. Show that :

∠ADC : ∠C = 4 : 1.

Using the information, given in each of the following figures, find the values of a and b.

In the following figure; AB is the largest side and BC is the smallest side of triangle ABC.

Write the angles x°, y° and z° in ascending order of their values.