This test has 9 questions worth 20 points in total. It covers constructions with a compass and straightedge, and the measurements and reasons that connect to them. Show your work, write full sentences when explaining, and use no calculator. You have 45 minutes.
- Grade: Geometry
- Chapter: Geometric Constructions
- Common Core: G-CO.D.12, G-CO.D.13
- Time: 45 minutes
- Total: 20 points (Question 1: 2 pts; Question 2: 2 pts; Question 3: 3 pts; Question 4: 2 pts; Question 5: 2 pts; Question 6: 2 pts; Question 7: 3 pts; Question 8: 2 pts; Question 9: 2 pts)
Question 1: Perpendicular bisector measurements (2 points)
Arcs of radius 13 cm centered at \(A\) and \(B\) cross at \(P\) and \(Q\), where \(AB=10\text{ cm}\). Line \(PQ\) meets \(AB\) at \(M\).
- Find \(AM\). (1 point)
- Find \(PQ\). (1 point)
Question 2: Angle bisector with a variable (2 points)
Ray \(\vec{BD}\) bisects \(\angle ABC\), with \(m\angle ABD=(4x-6)^{\circ}\) and \(m\angle DBC=(3x+9)^{\circ}\).
Find \(x\) (1 point) and \(m\angle ABC\) (1 point).
Question 3: Perpendicular from a point (3 points)
Point \(P\) is not on line \(l\). Describe, in order, the steps to construct the line through \(P\) perpendicular to \(l\) with a compass and straightedge.
Question 4: Justify an angle copy (2 points)
In the construction, \(AP=AQ=DP^{\prime}=DQ^{\prime}\) and the compass width \(PQ\) was copied to \(P^{\prime}Q^{\prime}\). Explain why \(\angle QAP\) is congruent to \(\angle Q^{\prime}DP^{\prime}\).
Question 5: Parallel line construction (2 points)
A student constructs a line through \(P\) parallel to line \(l\) by copying the \(58^{\circ}\) angle at \(Q\) to point \(P\).
- What is the measure of the copied angle at \(P\)? (1 point)
- Which theorem shows that the new line is parallel to \(l\)? (1 point)
Question 6: Equilateral triangle (2 points)
Triangle \(ABC\) is constructed on \(\overline{AB}\) with \(AB=9\text{ in}\) by drawing arcs of radius \(AB\) from \(A\) and \(B\).
- Find the perimeter of triangle \(ABC\). (1 point)
- Find \(m\angle C\) and give a reason. (1 point)
Question 7: Regular hexagon in a circle (3 points)
A regular hexagon is inscribed in a circle of radius 8 cm using the compass-and-straightedge method.
- Find the length of each side. (1 point)
- Find the perimeter. (1 point)
- Find the measure of each interior angle of the hexagon. (1 point)
Question 8: Square in a circle (2 points)
Square \(ABCD\) is inscribed in a circle with center \(O\) and diameter 12 in.
- Find \(AC\). (1 point)
- Find \(m\angle AOB\). (1 point)
Question 9: Compass width (2 points)
Maya wants to bisect \(\overline{AB}\), where \(AB=8\text{ cm}\). She sets the compass to 3 cm and draws arcs centered at \(A\) and \(B\). Explain what goes wrong, and give the condition that the compass radius must meet.
See every chapter on the Geometry math page.



