What is a necessary step for constructing perpendicular lines through a point on a line?

draw a line that intersects the first line at an acute angle using a straightedge.
draw a ray that intersects the first line at an acute angle using a straightedge.
draw arcs on either side of a given point on the line.
draw arcs on either side of a given point off the line.

answer: the proof is mentioned below.

step-by-step explanation:

since, given:   lines bc = ef

prove:   lines ac > ef

          statements                                           reason

1. bc=ef                                           1. given

2. ac= ab+bc                                 2. because b is the point between the  

                                                            line segment ac

3.   ac > bc                                       3. because if a line segment is equal to

                                                          the sum of two line segments then it is

                                                          always greater then each of these

                                                          individual line segments

4. ac > ef                                         4. by equality property.

the answer is d.x= 90°

y= 50°

arc lm= 100°

i got this one chief