standard_description: Use measures of center and measures of variability for numerical data from random samples to draw informal comparative inferences about two populations. For example, decide whether the words in a chapter of a seventh-grade science book are generally longer than the words in a chapter of a fourth-grade science book.
problem_activity: Suppose
$${{\overline{AB}}}$$
is a line segment and
D
is a point not on
$${{\overline{AB}}}$$
as pictured below.
[IMG]
Let
C
be the point so that
$${CD=AB}$$
,
$${\overleftrightarrow {CD} \parallel \overleftrightarrow {AB}}$$
and
ABCD
is a quadrilateral.
Draw
$${\overline {CD}}$$
using constructions.
Explain how you know that
$${\overleftrightarrow {CA} \parallel \overleftrightarrow {DB}}$$
.


aligns: no