A parallelogram is a figure which has its <em>opposite</em> sides to be <u>equal</u> and <u>parallel</u>. The <em>missing</em> reason in the proof is:
B. Substitution Angle Angle Postulate.
A <em>parallelogram</em> is a type of quadrilateral that has its <u>opposite</u> sides to be equal and parallel. The sum of its <em>internal</em> angles is .
To <u>prove</u> that ∠ BAD ≅ ∠ DCB, we have:
Given parallelogram ABCD;
<BAC ≅ <ACD (alternate angle theorem)
<DAC ≅ <ACB (alternate angle theorem)
<BAC + <DAC = <BAD
Also,
<BCA + <DCA = <BCD
Therefore,
<BAD ≅ <DCB (Substitution Angle Angle Postulate)
Thus, the <u>missing</u> reason in the partial proof is:
option B. Substitution Angle Angle Postulate
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