Chord parallel to AB and 2CD=AB

In summary, in this conversation the participants discuss a geometry problem involving a circle with diameter AB, a chord CD parallel to AB, and a tangent at point B that meets the line AC at point E. They discuss various methods to prove that AE is equal to 2AB, with one participant suggesting to build a trapezoid and another using the Pythagorean theorem. Ultimately, they come to the conclusion that the triangle BAE is a right triangle with a 60 degree angle, which leads to the solution of AE being equal to 2AB.
  • #1
himanshu121
653
1
AB is the diameter of a circle CD is a chord parallel to AB and 2CD=AB. The tangent at B meets the line AC produced at E. Prove that AE=2AB.

I'm finding no way to solve this ?

Still i thought of applying AE*CE=BE2 but that is not enough to slove the pro ?

Any other Hint to solve
 
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  • #2
So A and C are on the same end of the chords?

Let O be the centre of the circle

the triangle OAC is equilateral, because the triangle OCD is and everything is symmetric.. well, convince yourself somehow

so angle BAE is 60,

so AB/AE = cos60 = 1/2; AE=d. QED

Opposite ends of te chords gives you...?
 
  • #3
i think you should bulid a trapozoid with CD and AB (with two sides equals to each other and to the small base-CD) and to see that we have THE TRAINGLE BAE as a right triangle because the angle between radius and a tangent is 90.
here are my computations that brought to the answer:
BE^2=CE*AE
AB^2+BE^2=AE^2 (PYTHAGORAS THEOREM)
AB^2+CE*AE=AE^2
AB^2=AE(AE-CE)=AE*CE
CE=CD=AB/2
AB^2/CE=AE
AB^2/(AB/2)=AE
2AB=AE

so you were half right himanshu :wink:
 
  • #4
i have an illustration of the triangle and trapaoid the problem is my scanner doesn't work so i can't upload it here, sorry.
 
  • #5
Ya i got it
I was half way write upto formation of equation and it just required manipulations & rearrangement

Ya i convinced myself for equilateral triangle
Thnxs
 

What does "Chord parallel to AB and 2CD=AB" mean?

This statement refers to a geometric concept in which two lines, the chord and the line AB, are parallel to each other. Additionally, the length of line CD is twice the length of line AB.

How can I determine if a chord is parallel to a given line AB?

To determine if a chord is parallel to a given line AB, you can use the following criteria: if the angle between the chord and the line AB is 90 degrees, they are parallel. Alternatively, if the slope of both lines is the same, they are parallel.

What does the equation 2CD=AB represent in this context?

The equation 2CD=AB represents the relationship between the lengths of the lines CD and AB. It states that the length of line CD is exactly twice the length of line AB.

What is the significance of a chord being parallel to a given line AB?

When a chord is parallel to a given line AB, it creates two congruent triangles. This property is useful in various geometric proofs and calculations.

How can I apply the concept of a chord parallel to AB and 2CD=AB in real-world situations?

The concept of a chord parallel to AB and 2CD=AB can be applied in various fields such as architecture, engineering, and design. For example, it can be used to create symmetrical and aesthetically pleasing structures or to determine the length of a chord in a bridge or arch.

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