Question

SBC is an isosceles triangle with main vertex S.

Answer 1

Answer + Step-by-step explanation:

1) D be the symmetric of B with respect to C then CD = BC

A the symmetric of C with respect to B then AB = BC

We obtain :

CD = BC

AB = BC

Then AB = CD

2) m∠SBA = 180 - SBC = 180 - SCB = m∠SCD

3) we have :

BA = CD

BS = CS

m∠SBA = m∠SCD

Then

the triangles SBA and SCD are congruent

4)

the triangles SBA and SCD are congruent Then SA = SD

Therefore SAD is an isosceles triangle.