Triangle proofs: fill in the missing step or reason

Grade 10 Math Worksheet - Challenge Me

NameDate

Circle the best answer.

  1. Kira sews a seam SY on a sail SUW; the two bottom pieces have lengths written with x. Which reason fills the blank?

    • Subtraction property of equality
    • Definition of midpoint
    • Addition property of equality
    • Multiplication property of equality
  2. Milo cuts a triangle sandwich DCY along median DS; the two edge pieces have lengths written with x. Which reason fills the blank?

    • Given
    • Division property of equality
    • Addition property of equality
    • Definition of median
  3. Read this first

    Use this

    Given: CD ≅ CF, and CQ is a median of triangle CDF. Prove: CQ bisects ∠DCF. Ladder: 1. CD ≅ CF -- Given; 2. CQ is a median of triangle CDF -- Given; 3. Q is the midpoint of DF -- Definition of median; 4. ? -- Definition of midpoint; 5. CQ ≅ CQ -- Reflexive property; 6. triangle CDQ ≅ triangle CFQ -- SSS; 7. ∠DCQ ≅ ∠FCQ -- CPCTC; 8. CQ bisects ∠DCF -- Definition of angle bisector.

  4. Noah shows that the median CQ of road sign CDF splits its top angle evenly. Which statement fills the blank?

    • CQ bisects ∠DCF
    • CD ≅ DQ
    • DQ ≅ FQ
    • CQ ≅ DF
  5. Use this

    Sketch, not to scale: triangle SWY with S at the top and base WY; segment SU runs from S to point U on WY. Marked: SW and SY with one tick each. Given: SW ≅ SY, and SU is a median of triangle SWY. Prove: SU bisects ∠WSY. Ladder: 1. SW ≅ SY -- Given; 2. SU is a median of triangle SWY -- Given; 3. U is the midpoint of WY -- Definition of median; 4. ? -- Definition of midpoint; 5. SU ≅ SU -- Reflexive property; 6. triangle SWU ≅ triangle SYU -- SSS; 7. ∠WSU ≅ ∠YSU -- CPCTC; 8. SU bisects ∠WSY -- Definition of angle bisector.

  6. Pia shows that the median SU of roof SWY splits its top angle evenly. Which statement fills the blank?

    • SW ≅ WU
    • WU ≅ YU
    • SU bisects ∠WSY
    • SU ≅ WY
  7. Ren shows that the median GD of tent front GHV splits its top angle evenly. Which statement fills the blank?

    • △GHD ≅ △GVD
    • GD bisects ∠HGV
    • △GHD ≅ △DVG
    • △GHV ≅ △GVD
  8. Tala shows that the median FY of pyramid face FCU splits its top angle evenly. Which statement fills the blank?

    • △FCU ≅ △FUY
    • FY bisects ∠CFU
    • △FCY ≅ △FUY
    • △FCY ≅ △YUF
  9. Use this

    Given: QS ≅ QW, and QH is a median of triangle QSW. Prove: QH bisects ∠SQW. Ladder: 1. QS ≅ QW -- Given; 2. QH is a median of triangle QSW -- Given; 3. H is the midpoint of SW -- Definition of median; 4. SH ≅ WH -- Definition of midpoint; 5. QH ≅ QH -- Reflexive property; 6. triangle QSH ≅ triangle QWH -- SSS; 7. ? -- ?; 8. QH bisects ∠SQW -- Definition of angle bisector.

  10. Zee shows that the seam QH of an isosceles sail QSW splits its top angle evenly. Which statement and reason fill the blanks?

    • ∠SQH ≅ ∠WQH — SSS
    • ∠SQH ≅ ∠WQH — CPCTC
    • ∠SQH ≅ ∠WQH — Reflexive property
    • QH bisects ∠SQW — Definition of angle bisector
  11. Use this

    Given: VD ≅ VG, and VC is a median of triangle VDG. Prove: VC bisects ∠DVG. Ladder: 1. VD ≅ VG -- Given; 2. VC is a median of triangle VDG -- Given; 3. C is the midpoint of DG -- Definition of median; 4. DC ≅ GC -- Definition of midpoint; 5. VC ≅ VC -- Reflexive property; 6. triangle VDC ≅ triangle VGC -- SSS; 7. ? -- ?; 8. VC bisects ∠DVG -- Definition of angle bisector.

  12. Ari shows that the median VC of an isosceles ramp side VDG splits its top angle evenly. Which statement and reason fill the blanks?

    • ∠DVC ≅ ∠GVC — CPCTC
    • ∠DVC ≅ ∠GVC — SSS
    • VC bisects ∠DVG — Definition of angle bisector
    • ∠DVC ≅ ∠GVC — Reflexive property
  13. Bo shows that the median UG of an isosceles pizza slice UCF splits its tip angle evenly. Which statement and reason fill the blanks?

    • △UCG ≅ △UFG — SAS
    • ∠CUG ≅ ∠FUG — CPCTC
    • △UCG ≅ △UFG — SSS
    • △UCG ≅ △GFU — SSS
  14. Esme shows that the median YW of an isosceles road sign YDS splits its top angle evenly. Which statement and reason fill the blanks?

    • △YDW ≅ △YSW — SSS
    • ∠DYW ≅ ∠SYW — CPCTC
    • △YDW ≅ △WSY — SSS
    • △YDW ≅ △YSW — SAS
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Triangle proofs: fill in the missing step or reason

Answer Key - Grade 10 Math Worksheet - Challenge Me

Circle the best answer.

  1. Kira sews a seam SY on a sail SUW; the two bottom pieces have lengths written with x. Which reason fills the blank?

    • Subtraction property of equality
    • Definition of midpoint
    • Addition property of equality
    • Multiplication property of equality
  2. Milo cuts a triangle sandwich DCY along median DS; the two edge pieces have lengths written with x. Which reason fills the blank?

    • Given
    • Division property of equality
    • Addition property of equality
    • Definition of median
  3. Read this first

    Use this

    Given: CD ≅ CF, and CQ is a median of triangle CDF. Prove: CQ bisects ∠DCF. Ladder: 1. CD ≅ CF -- Given; 2. CQ is a median of triangle CDF -- Given; 3. Q is the midpoint of DF -- Definition of median; 4. ? -- Definition of midpoint; 5. CQ ≅ CQ -- Reflexive property; 6. triangle CDQ ≅ triangle CFQ -- SSS; 7. ∠DCQ ≅ ∠FCQ -- CPCTC; 8. CQ bisects ∠DCF -- Definition of angle bisector.

  4. Noah shows that the median CQ of road sign CDF splits its top angle evenly. Which statement fills the blank?

    • CQ bisects ∠DCF
    • CD ≅ DQ
    • DQ ≅ FQ
    • CQ ≅ DF
  5. Use this

    Sketch, not to scale: triangle SWY with S at the top and base WY; segment SU runs from S to point U on WY. Marked: SW and SY with one tick each. Given: SW ≅ SY, and SU is a median of triangle SWY. Prove: SU bisects ∠WSY. Ladder: 1. SW ≅ SY -- Given; 2. SU is a median of triangle SWY -- Given; 3. U is the midpoint of WY -- Definition of median; 4. ? -- Definition of midpoint; 5. SU ≅ SU -- Reflexive property; 6. triangle SWU ≅ triangle SYU -- SSS; 7. ∠WSU ≅ ∠YSU -- CPCTC; 8. SU bisects ∠WSY -- Definition of angle bisector.

  6. Pia shows that the median SU of roof SWY splits its top angle evenly. Which statement fills the blank?

    • SW ≅ WU
    • WU ≅ YU
    • SU bisects ∠WSY
    • SU ≅ WY
  7. Ren shows that the median GD of tent front GHV splits its top angle evenly. Which statement fills the blank?

    • △GHD ≅ △GVD
    • GD bisects ∠HGV
    • △GHD ≅ △DVG
    • △GHV ≅ △GVD
  8. Tala shows that the median FY of pyramid face FCU splits its top angle evenly. Which statement fills the blank?

    • △FCU ≅ △FUY
    • FY bisects ∠CFU
    • △FCY ≅ △FUY
    • △FCY ≅ △YUF
  9. Use this

    Given: QS ≅ QW, and QH is a median of triangle QSW. Prove: QH bisects ∠SQW. Ladder: 1. QS ≅ QW -- Given; 2. QH is a median of triangle QSW -- Given; 3. H is the midpoint of SW -- Definition of median; 4. SH ≅ WH -- Definition of midpoint; 5. QH ≅ QH -- Reflexive property; 6. triangle QSH ≅ triangle QWH -- SSS; 7. ? -- ?; 8. QH bisects ∠SQW -- Definition of angle bisector.

  10. Zee shows that the seam QH of an isosceles sail QSW splits its top angle evenly. Which statement and reason fill the blanks?

    • ∠SQH ≅ ∠WQH — SSS
    • ∠SQH ≅ ∠WQH — CPCTC
    • ∠SQH ≅ ∠WQH — Reflexive property
    • QH bisects ∠SQW — Definition of angle bisector
  11. Use this

    Given: VD ≅ VG, and VC is a median of triangle VDG. Prove: VC bisects ∠DVG. Ladder: 1. VD ≅ VG -- Given; 2. VC is a median of triangle VDG -- Given; 3. C is the midpoint of DG -- Definition of median; 4. DC ≅ GC -- Definition of midpoint; 5. VC ≅ VC -- Reflexive property; 6. triangle VDC ≅ triangle VGC -- SSS; 7. ? -- ?; 8. VC bisects ∠DVG -- Definition of angle bisector.

  12. Ari shows that the median VC of an isosceles ramp side VDG splits its top angle evenly. Which statement and reason fill the blanks?

    • ∠DVC ≅ ∠GVC — CPCTC
    • ∠DVC ≅ ∠GVC — SSS
    • VC bisects ∠DVG — Definition of angle bisector
    • ∠DVC ≅ ∠GVC — Reflexive property
  13. Bo shows that the median UG of an isosceles pizza slice UCF splits its tip angle evenly. Which statement and reason fill the blanks?

    • △UCG ≅ △UFG — SAS
    • ∠CUG ≅ ∠FUG — CPCTC
    • △UCG ≅ △UFG — SSS
    • △UCG ≅ △GFU — SSS
  14. Esme shows that the median YW of an isosceles road sign YDS splits its top angle evenly. Which statement and reason fill the blanks?

    • △YDW ≅ △YSW — SSS
    • ∠DYW ≅ ∠SYW — CPCTC
    • △YDW ≅ △WSY — SSS
    • △YDW ≅ △YSW — SAS