1. Which criterion can be used to prove two triangles with sides 3 cm, 4 cm, and 5 cm are congruent?
- ASSS
- BSAS
- CASA
- DRHS
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Answer: A) SSS
The SSS criterion is used when all three sides of two triangles are equal.
Class 7 Congruence of Triangles — practice questions with answers
Geometry · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
2. A triangle has sides of 10 cm, 24 cm, and 26 cm. If a second triangle is congruent to it by SSS, what is its longest side length?
- A26 cm
- B10 cm
- C24 cm
- D34 cm
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Answer: A) 26 cm
Congruent triangles by SSS have all corresponding sides equal, so the longest side is 26 cm.
3. A right-angled triangle has legs of 6 cm and 8 cm. What is the length of its hypotenuse?
- A10
- B20
- C11
- D9
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Answer: A) 10
By the Pythagorean theorem, hypotenuse = = = = 10 cm.
4. Triangle ABC is congruent to triangle DEF. If angle A = 55° and angle B = 65°, what is the measure of angle F?
- A120
- B66
- C54
- D60
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Answer: D) 60
Angle C = 180 - 55 - 65 = 60 degrees. Since C corresponds to F, angle F = 60 degrees.
5. In triangles ABC and ADC, AB = AD, CB = CD and AC is common. Which criterion proves the two triangles congruent?
- ASSS
- BSAS
- CASA
- DRHS
Show answer
Answer: A) SSS
AB = AD, CB = CD and AC = AC (common side) give three equal pairs of sides, so SSS proves congruence.
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