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Use the Hypotenuse-Leg Congruence Theorem and the definitions of bisector and arc bisector.
Statements
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Reasons
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1. ⊙ P and KM⊥JP
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1. Given
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2. ∠ PLK and ∠ PLM are right angles
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2. Definition of perpendicular segments
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3. ∠ PLK ≅ ∠ PLM
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3. All right angles are congruent
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4. LP≅LP
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4. Reflexive Property of Congruence
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5. KP≅ MP
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5. All radii of a circle are congruent
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6. △ LKP ≅ △ LMP
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6. Hypotenuse-Leg Congruence Theorem
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7. LK ≅ LM and ∠ KPL ≅ ∠ MPL
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7. Definition of congruent triangles
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8. JP bisects KM
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8. Definition of bisector
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9. m∠ KPL=m∠ MPL
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9. Definition of congruent angles
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10. mKJ = m∠ KPL and mJM=m∠ MPL
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10. Definition of arc measures
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11. mKJ = mJM
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11. Substitution
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12. JP bisects KM
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12. Definition of arc bisector
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Let's consider a circle centered at P, a chord KM, and a radius JP such that KM⊥ JP.
Next, since △ LKP and △ LMP are right triangles, we can apply the Hypotenuse-Leg Congruence Theorem to conclude that these triangles are congruent. △ LKP ≅ △ LMP ↙ ↘ LK ≅ LM ∠ KPL ≅ ∠ MPL We can conclude that L is the midpoint of KM and that JP bisects KM. Also, by the definition of arc measure, we can write the following two equations. mKJ = m∠ KPL mJM = m∠ MPL Since the measures written on the right-hand side are equal, we conclude that both arcs have the same measure. This implies that JP bisects KM.
Given: & ⊙ P, KM⊥JP Prove: & JP bisectsKMandKM Let's summarize the proof we did in the following two-column table.
Statements
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Reasons
|
1. ⊙ P and KM⊥JP
|
1. Given
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2. ∠ PLK and ∠ PLM are right angles
|
2. Definition of perpendicular segments
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3. ∠ PLK ≅ ∠ PLM
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3. All right angles are congruent
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4. LP≅LP
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4. Reflexive Property of Congruence
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5. KP≅ MP
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5. All radii of a circle are congruent
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6. △ LKP ≅ △ LMP
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6. Hypotenuse-Leg Congruence Theorem
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7. LK ≅ LM and ∠ KPL ≅ ∠ MPL
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7. Definition of congruent triangles
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8. JP bisects KM
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8. Definition of bisector
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9. m∠ KPL=m∠ MPL
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9. Definition of congruent angles
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10. mKJ = m∠ KPL and mJM=m∠ MPL
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10. Definition of arc measures
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11. mKJ = mJM
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11. Substitution
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12. JP bisects KM
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12. Definition of arc bisector
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