The missing statement in the proof specified is given by: Option B: ∠BCA≅∠DCB
What is reflexive property of congruence?
The reflexive property of congruence says that the considered geometric quantity, whether it be angle, line segment, or shape etc, is congruent to itself.
For this case, the third step has bottom line: "Reflexive Property of Congruence"
And the fourth step then concludes that ΔABC~ΔBDC by AA criterion for similarity
Since in the second step, it was proven that ∠ABC≅∠BDC
So, in third step, we need to show another angle pair of ΔABC and ΔBDC being congruent so that fourth step applies angle-angle similarity, which needs to angles of two considered triangles to be congruent.
In triangles ΔABC and ΔBDC, the common angle is internal angle C.
Thus, by reflexive property, it is congruent to itself.
From triangle ABC, we get the notation for internal angle C as: [tex]\angle ACB \: or \: \angle BCA[/tex] (both will work)
From triangle BDC, we get the notation for internal angle C as:
[tex]\angle DCB \: or \: \angle BCD[/tex](both will work).
They are congruent. The second option is considering the angle C, thus:
∠BCA≅∠DCB (second option) is the missing statement.
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