What postulate or theorem justifies the statement?

Question

http://tinypic.com/view.php?pic=1dzdxw&s=2

1) What postulate or theorem justifies the statement triangle ABC~ triangle RST?

2) What postulate or theorem justifies the statement triangle SQR ~triangle VTU?

Thanks.

Answer 1

If two triangles have an equal angle and the corresponding sides including that angle proportional, then the triangles are similar

If two triangle have their corresponding sides proportional, the triangles are similar