1.) congruent by SAS
2.) congruent by SSS
3.) Not enough information
4.) congruent by SAS
5.) Vertical angles theorem; the additional information needed is ∠WXV≅∠YXZ so that SAS can be applied.
6.) Yes, triangles SPQ and QRS can be prove congruent via SAS. This is because opposite sides of rectangles are parallel and congruent, so leg 2 (the base) of both right triangles is congruent. It is shown that ∠SPQ≅∠QRS because they are both right angles, so they both measure 90.° Lastly, sides SP and QR are shown as congruent, which makes sense because opposite sides of rectangles are parallel and congruent. Therefore, we have a pair of corresponding, congruent sides, a pair of included corresponding, congruent angles, and another pair of corresponding, congruent sides; therefore, △SPQ≅△QRS via SAS.