In ΔBAX and ΔCDX,
AX=DX………(given)
BX=CX………(given)
∠AXB=∠DXC ……….(vertically opposite angles are equal) [1 mark]
ΔBAX≅ΔCDX …… (SAS postulate) [1 mark]
Two triangles ABC and DBC have common base BC. Suppose AB = DC and ∠ABC = ∠BCD. Prove that AC = BD.