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10th grade Triangle congruence: SSS and SAS worksheet

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Triangle congruence: SSS and SAS

Grade 10 Math Worksheet

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Circle the best answer, or write your answer on the line.

  1. Read this first

    Use this

    Two triangles, not to scale, with the given parts marked and labeled. The matching table under them has ✓ on the three given rows.

  2. Jun checks two tent flaps: DF = SU = 9 cm, FG = UV = 12 cm and m∠F = m∠U = 40°. Do these facts prove △DFG ≅ △SUV?

    • No: SAS is not enough; all three sides must be given.
    • Yes, by SAS: ∠F is between DF and FG.
    • No: the angle must be given before the sides.
  3. Kira checks two quilt patches: CH = YQ = 14 cm, CW = YS = 10 cm and m∠C = m∠Y = 55°. Do these facts prove △CHW ≅ △YQS?

    • Yes, by SAS: ∠C is between CH and CW.
    • No: the angle must be given before the sides.
    • No: SAS is not enough; all three sides must be given.
  4. Luz checks two park shapes on a map: GQ = FD = 8 cm, QU = DH = 15 cm and m∠U = m∠H = 28°. Do these facts prove △GQU ≅ △FDH?

    • Yes, by SSA: two sides and an angle are equal.
    • No: ∠U is not between GQ and QU, so this is SSA.
    • Yes, by SAS: two sides and an angle are equal.
  5. Milo checks two castle flags: VY = GW = 11 cm, SY = CW = 13 cm and m∠S = m∠C = 48°. Do these facts prove △SVY ≅ △CGW?

    • No: ∠S is not between VY and SY, so this is SSA.
    • Yes, by SAS: two sides and an angle are equal.
    • Yes, by SSA: two sides and an angle are equal.
  6. Noah checks two kite halves, △DFG and △VSU. The figure gives their sides, with SU = (3x + 3) cm. What x gives △DFG ≅ △VSU by SSS?

  7. Use this

    Two triangles, not to scale. △CHQ: CH = 14 cm, HQ = 15 cm, CQ = 20 cm. △WYS: WY = 14 cm, YS = 15 cm, WS = (2x + 6) cm. The matching table under them is blank.

  8. Pia checks the two sides of a stepladder, △CHQ and △WYS. The figure gives their sides, with WS = (2x + 6) cm. What x gives △CHQ ≅ △WYS by SSS?

  9. Two triangles, not to scale. The matching table under them is blank. Tala checks two boat sails, △QSV and △GYC. The figure gives their sides, with GC = (2x + 5) cm. What x gives △QSV ≅ △GYC by SSS?

  10. “Two triangles, not to scale:” Ari checks two window panes. QW = DY and ∠W = ∠Y are marked. Which one more fact proves △CQW ≅ △HDY by SAS?

    • CQ = HD
    • CW = DY
    • CW = HY
  11. Bo checks two rug triangles. GS = YU and ∠G = ∠Y are marked. Which one more fact proves △GHS ≅ △YFU by SAS?

    • GH = FU
    • GH = YF
    • HS = FU
  12. “not to scale” Esme checks two paper triangles. UY = SC and ∠U = ∠S are marked. Which one more fact proves △UVY ≅ △SQC by SAS?

    • UV = SQ
    • UV = QC
    • VY = QC
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10th grade Triangle congruence: SSS and SAS worksheet – printable
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About this worksheet

Triangle congruence: SSS and SAS. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can say which angle is between two sides, and tell SAS from SSA.
  • I can decide whether the facts given prove two triangles congruent by SSS or SAS.
  • I can find the missing fact or the value of x that makes SSS or SAS work, including a side two triangles share.

Standard: G-CO.B.8

Words to know

SSS: Three pairs of equal sides prove two triangles congruent.

SAS: Two pairs of sides and the angle between them prove it.

included angle: The angle where two sides meet; its letter is in both side names.

SSA: Two sides and an angle not between them: not a rule, proves nothing.

shared side: One segment that belongs to both triangles; it matches itself.

vertical angles: Angles across from each other where two lines cross; always equal.

Common mistakes

Your child used an angle that is not between the two sides.

Your child thought three pairs of equal sides were not enough. Build two triangles from the same three straws and see they always match.

Your child checked two pairs of sides and stopped.

What to say

Ask: at which corner do the two sides meet?

Ask: does SSS need two pairs or three?

Questions parents ask

What is the most common mistake with triangle congruence: sss and sas?

Your child used an angle that is not between the two sides.

How can I help my child with triangle congruence: sss and sas?

Ask: at which corner do the two sides meet?

Are these 10th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More geometry

See all Geometry

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