Question

Geometry: write formal proofs, ASAP!!!!!

Answer 1

Two lines are said to be parallel if and only if the value of the angle between them is $180^{o}$.

Thus the required proofs for each question are stated below:

6. A bisector is a line that divides a given line or angle into two equal parts.

Thus to prove that: AD ║BC

Given that: AC ⊥ BD, then:

BX ≅ DX (midpoint property of a line)

<ADX ≅ <DBX (alternate angle property)

<DAX ≅ <BCX (alternate angle property)

<AXD ≅ <BXC (vertical opposite angle property)

Also,

ΔAXD ≅ ΔBXC (congruent property of similar triangles)

Therefore, it can be deduced that;

AD ║BC

7. Given: CD ≅ CE

<B ≅ <D

proof: AB ║DE

<ABC  ≅EDC

Thus,

CB  ≅ CA (congruent property of similar triangle)

<BAC  ≅ <EDC (alternate angle property)

ABC  ≅ <DEC (alternate angle property)

Also,

CA ≅ CB (congruent side of similar triangles)

ΔABc ≅ ΔCDE (congruent property of similar triangles)

Thus,

AB ║DE (congruent property)

8. Prove: AB ║ DE

Given: <1 ≅ < 3

Then,

<1 ≅ <2 ≅ <3 ≅ $90^{o}$

So that,

BC ≅ EF

also,

<1 + <2 = $180^{o}$ (supplementary angles)

Therefore it can be inferred that;

AB ║ DE (congruent property of parallel lines intersected by transversals)

For more clarifications on parallel lines, visit: brainly.com/question/24607467

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