If the markings were missing on this quadrilateral, how would you go about verifying what shape it is?

A) Because this is a rectangle, I would show that each vertex is made up with lines that have opposite reciprocal slopes.
B) Because this is a parallelogram, I would show that each vertex is made up with lines that have opposite reciprocal slopes.
C) Because this is a parallelogram, I would show that all four sides are congruent.
D )Because this is a parallelogram, I would show that opposite sides have the same slope.

Option A: Because this is a rectangle, I would show that each vertex is made up with lines that have opposite reciprocal slopes.

Step-by-step explanation:

A rectangle is a quadrilateral with four right angles.

Each right angle is made up of two perpendicular lines forming a vertex

And then proving this that all perpendicular lines have negative reciprocal slope.

It isn't always necessary  to employ the idea of using a parallelogram first although it might be useful.

step-by-step explanation:

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl