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.
