Question

PLEAAASEEE HELP AND EXPLAIN ASAP

Answer 1

It is a and b cause i learned that before

Answer 2

We know, widest angle is always opposite to the largest side of the triangle, as largest side is 50 here (which is backward to house) so largest angle would be opposite to it. So, that corner will be touched by  Fence A & B

"Proportionality Theorem" compares the sides of the same triangle 
Here, According to that theorem, 
ST / RS = UT / PU

If FG is an altitude, then <DFG  is an right triangle.
In short, Your Answer would be Option B

For last question here, remember, longest side must be greater than either side, and must be smaller than sum of those smaller sides.