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Congruent Triangles (Year 9)

Free printable UK Year 9 (Key Stage 3) maths worksheet: use the SSS, SAS, ASA and RHS congruence criteria to find missing sides and angles.

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Grade 8 · Math worksheet
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Math

Congruent Triangles

Use the congruence criteria (SSS, SAS, ASA, RHS) to find each missing side or angle, and name the criterion used.

  1. 1.
    Triangle ABC has sides AB = 12 cm, BC = 11 cm, CA = 12 cm. Triangle DEF is congruent to triangle ABC (SSS), with DE = 12 cm and EF = 11 cm. Find DF, and name the congruence criterion used.
  2. 2.
    Triangle ABC has sides AB = 12 cm, BC = 12 cm, CA = 7 cm. Triangle DEF is congruent to triangle ABC (SSS), with DE = 12 cm and EF = 12 cm. Find DF, and name the congruence criterion used.
  3. 3.
    Triangle ABC has AB = 6 cm, BC = 13 cm and angle B = 34 degrees. Triangle DEF is congruent to triangle ABC (SAS), with DE = 6 cm and angle E = 34 degrees. Find EF, and name the congruence criterion used.
  4. 4.
    Triangle ABC has AB = 5 cm, BC = 10 cm and angle B = 69 degrees. Triangle DEF is congruent to triangle ABC (SAS), with DE = 5 cm and angle E = 69 degrees. Find EF, and name the congruence criterion used.
  5. 5.
    Triangle ABC has angle A = 32 degrees, angle B = 60 degrees and side AB = 8 cm. Triangle DEF is congruent to triangle ABC (ASA), with angle D = 32 degrees and side DE = 8 cm. Find angle E, and name the congruence criterion used.
  6. 6.
    Triangle ABC has angle A = 41 degrees, angle B = 44 degrees and side AB = 8 cm. Triangle DEF is congruent to triangle ABC (ASA), with angle D = 41 degrees and side DE = 8 cm. Find angle E, and name the congruence criterion used.
  7. 7.
    Right-angled triangle ABC has the right angle at B, hypotenuse AC = 16 cm, and AB = 8 cm. Right-angled triangle DEF has the right angle at E, hypotenuse DF = 16 cm, and DE = 8 cm. Explain why triangle DEF is congruent to triangle ABC, and name the criterion.
  8. 8.
    Right-angled triangle ABC has the right angle at B, hypotenuse AC = 15 cm, and AB = 10 cm. Right-angled triangle DEF has the right angle at E, hypotenuse DF = 15 cm, and DE = 10 cm. Explain why triangle DEF is congruent to triangle ABC, and name the criterion.
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