2. Geometry Mini-Lesson AB = 4, DE = 4, m BAC = m EDF
These two triangles were on Yin's geometry exam. Which of the following statements will prove that triangle ABC is congruent to triangle DEF?
AB = 4, DE = 4, m BAC = m EDF
BC = 6, EF = 6, m BAC = m EDF
AB = 4, DE = 4, m ABC = m DEF
BC = 6, EF = 6, m ABC = m DEF
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

3. Geometry Mini-Lesson
Given that m BCD = 50°, which of the following statements is sufficient to prove that ΔBCD is an isosceles triangle?
m ABD = 100°
m BDC + m CBD + 50° = 180°
m BDC + 50° = m ABD
m ABD + m CBD = 180°
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

4. Geometry Mini-Lesson
Given that m BAC = 20°, which of the following statements will prove Δ ABC is isosceles?
m ABC + m BCA + 20° = 180°
m ABC + 20° = m BCD
m BCD = 40°
m ACB + m BCD = 180°
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

5. Geometry Mini-Lesson AE = DE AB = CD m EAB = m EDC m EBA = m ECD
Use the figure below to determine which of the following conditions is sufficient to prove that ΔBEC is isosceles?
AE = DE
AB = CD
m EAB = m EDC
m EBA = m ECD
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

6. Geometry Mini-Lesson m ADC = 90° m BAD = 90° m BCD = 90° m ACB = 60°
On Jamal's geometry test, quadrilateral ABCD is inscribed in a circle. Use the figure to determine which of the following statements is sufficient to prove that ΔABC is a right triangle?
m ADC = 90°
m BAD = 90°
m BCD = 90°
m ACB = 60°
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

7. Geometry Mini-Lesson
Tomas saw the following figure of parallelogram ABCD in his geometry book. Which of the following statements will prove that parallelogram ABCD is a rectangle?
m ABC + m BCD = 180°
m ABC + m CDA = 180°
m BCD + m CDA = 180°
m CDA + m DAB = 180°
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

8. Geometry Mini-Lesson
Janet makes the conjecture that line p is also parallel to line r. What must the value of y be for her conjecture to be correct?
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

9. Geometry Mini-Lesson AB = 7, CD = 7, m ABC = m ADC
The following figure was on a quiz in Jaime's geometry class. Which of the following statements will prove that ΔABC is congruent to ΔCDA?
AB = 7, CD = 7, m ABC = m ADC
AD = 10, BC = 10, m ACD = m BAC
AB = 7, CD = 7, m CAD = m ACB
AD = 10, BC = 10, m ACB = m CAD
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.

10. Geometry Mini-Lesson
Maria inscribed ΔABC in a circle. Which of the following statements will prove that ΔABC is a right triangle?
BAC is acute.
ACB is obtuse.
AB = 3, AC = 5
Arc ABC is a semicircle.
MA.912.G.8.4: Make conjectures with justifications about geometric ideas. Distinguish between information that supports a conjecture and the proof of a conjecture.