Geometrical (circle) Proofs - Help

In summary: For Q(2), I'm assuming that point A is on the same circle as point B, and point C is on the same circle as point D. In summary, the first question is unclear and the second question asks to prove that AE is parallel to CF when AB and CD are parallel chords and BF and DE are parallel chords.
  • #1
robobuggg
1
0
Q1
Two circles intersect at P and Q. Two parallel line segments APC and BQD are drawn to meet one circle at A and C, and the other circle at B and D. PB and PD are diameters of their respective circles. Prove that points B, Q and D are collinear.

Q2
AB and CD are two parallel chords of a circle. If two other chords BF and DE are drawn such that they are parallel, prove that AE is parallel to CF.


For the first question, I'm not even sure how to draw it, as I don't see how A and C could be point on the same circle if the line goes through APC. I also don't understand why it's asking to prove BQD is collinear if it has already said that BQD is a (straight) line segment.

I've drawn a diagram for Q2, but I find that it's difficult to always know where to start with proofs. Any help would be much appreciated :)
 
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  • #2
robobuggg said:
For the first question, I'm not even sure how to draw it, as I don't see how A and C could be point on the same circle if the line goes through APC. I also don't understand why it's asking to prove BQD is collinear if it has already said that BQD is a (straight) line segment.
Hi robobuggg, http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

I agree, Q(1) doesn't make sense.
 
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1. What is a geometrical proof?

A geometrical proof is a logical argument that uses the principles of geometry to demonstrate the truth of a statement. It involves using definitions, axioms, and previously proven theorems to arrive at a conclusion.

2. Why are geometrical proofs important?

Geometrical proofs are important because they provide a rigorous and systematic way of proving mathematical statements. They also help us understand the underlying principles and relationships in geometry.

3. What is the most common method for writing a geometrical proof?

The most common method for writing a geometrical proof is the two-column proof. This method involves writing the statements (facts or previous theorems) in one column and the reasons (axioms, definitions, or previously proven theorems) in the other column.

4. How do I know which theorem or property to use in a geometrical proof?

When writing a geometrical proof, it is important to carefully analyze the given information and the statement to be proven. Look for any given properties or relationships that can help you arrive at the conclusion. If you are stuck, try working backwards from the desired conclusion.

5. Can I use diagrams in a geometrical proof?

Yes, diagrams are often used in geometrical proofs to help visualize the given information and the reasoning behind each step. However, it is important to remember that the written statements and reasons are the main components of a proof, and the diagram is just a visual aid.

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