Question

from unit 1, lesson 2 starting with two marked points, a and b, precisely describe the straightedge and compass moves required to construct the triangle abc in this diagram.

Explanation:

Step1: Set compass width

Set the compass width to the length of segment $AB$.

Step2: Draw circle from point A

Place the compass - point at $A$ and draw a circle.

Step3: Draw circle from point B

Without changing the compass width, place the compass - point at $B$ and draw a circle. The two circles intersect at two points. Let one of the intersection points be $C$.

Step4: Connect points

Use a straightedge to connect points $A$ to $C$, $B$ to $C$, and $A$ to $B$ to form triangle $ABC$.

Answer:

1. Set compass width to $AB$.
2. Draw a circle centered at $A$.
3. Draw a circle centered at $B$ with the same width.
4. Connect $A$ to $C$, $B$ to $C$, and $A$ to $B$.