Step-by-step explanation:
1. AD and EC intersects at B.. (given)
[tex]2.\: \angle ABE \cong \angle CBD\\ (vertically\:opposite\: \angle 's) \\\\[/tex]
[tex]3.\: \frac{AB}{DB} =\frac{12}{4}=\frac{3}{1}..(1)\\\\ [/tex]
[tex] 4.\:\frac{EB}{CB} =\frac{15}{5}=\frac{3}{1}..(2)\\\\ [/tex]
[tex]5.\: \frac{AB}{DB} =\frac{EB}{CB} ..\{from\: (1)\:\&\:(2)\}\\(Proportion \:of \: corresponding \:sides) [/tex]
[tex]6.\: \therefore \triangle ABE \sim \triangle DBC.. (By\:SAS) [/tex]
