Add Two 90
Subtract Both Sides 2
Add Term to Both Sides 7
Transitive Property of Equality Variation 2
Collinear Then 180
Converse of the Supplementary Angles Theorem
Transitive Property of Equality Variation 1
Angle Symmetry Example 2
Distance Property 2
Distance Property 1
Subtract Both Sides
Add Term to Both Sides 6
Vertical Angles
Angle Addition Theorem
Collinear Angles Property 9
Collinear Angles B
Exterior Angle
Exterior Angle B
Collinear Angles Property 10
Collinear Angles Property 3
Collinear Angles Property 3 B
Collinear Angles Property 3 C
alternate interior angles then parallel
Aia Then Parallel 3
Interior Supplementary Then Parallel
ParallelThenAIA
Parallelthenaiashort
Parallel Then Aia Short Mirror
Angle Symmetry 4
Angle Symmetry Example
If Parallelogram Diagonal Then Congruent Triangles
If Parallelogram Then Sides Congruent B
If Parallelogram Then Sides Congruent B2
Distance Property 3
Angle Swap
Commutative Property Example 2
Commutative Property Variation 1
Substitution 2
Substitution 8
Subtraction Example 2
Add Number to Both Sides
Add Number to Both Sides 2
Congruent Triangles to Distance 3
Transitive Property Application 2
Angles of an Isosceles Triangle
Angle Symmetry 2
Isosceles Triangle B
Propagated Transitive Property 3
Angle Symmetry B
Substitution Example 10
Substitute First Term
Triangles Sum to 180
Equality Example
If Two Angles Equal Then Three Angles Equal
Angle Angle Side Triangle
Angle Angle Side Triangle 2
Congruent Triangle Transitive Property
Hypotenuse And Leg Then Right Triangle Congruent
Collinear Points
If Diagonals Congreuent Then Isosceles Trapezoid

Proof: Angle Swap

Let's prove the following theorem:

if m∠DXY = 90 and m∠DXY = m∠DXB, then m∠BXD = 90

D X Y B

Proof:

View as a tree | View dependent proofs | Try proving it

Given
1 m∠DXY = 90
2 m∠DXY = m∠DXB
Proof Table
# Claim Reason
1 m∠DXB = 90 if m∠DXY = m∠DXB and m∠DXY = 90, then m∠DXB = 90
2 m∠BXD = 90 if m∠DXB = 90, then m∠BXD = 90
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