Problem finding exterior angle

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In summary, the conversation discusses finding the angle DAC in a triangle inscribed in a circle. The solution involves using the theorem that opposite angles subtended from the same chord add up to 180 degrees. By applying this theorem, the angle DAC is found to be 60 degrees.
  • #1
1/2"
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Homework Statement


Triangle ABC has been inscribed in the circle with center o.E is the midpoint of arc BC.DE is the diameter.E is joined to A, B and C.D is joined to A . If angle ABC =72 degrees and angle ACB = 48 degrees,
find angle DAC.
(I have attached the diagram given in book although its not a very good one)

Homework Equations


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The Attempt at a Solution


In this one what i did was,
i found angle BAC =(180-72-48)= 60 degrees
then i tried to subtend angle from the diameter to get 90 degree on the circumference but it did not help.
and i found the other angles like angle BEA=48 degrees and angle DEC= 72 degrees by the theorem the a chord extend equal angles on the circumference. But i can't get any further than this .Please help.
the answer given in my book is 60 degrees.
If I am going wrong somewhere please do let me know.
Thank you.
 

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  • #2
hi 1/2"! :smile:

use the theorem that opposite angles subtended from the same chord (ie opposite angles of an inscribed quadrilateral) add up to 180° :wink:
 
  • #3
I think i have already done it.
can you please be alittle more elaborate?
thanks.:smile:
 
  • #4
1/2" said:
I think i have already done it.
can you please be alittle more elaborate?
thanks.:smile:

i'm confused … if you've already done it, what's the problem?

and I've given you the full theorem … what is there to elaborate further? :confused:
 
  • #5
I am really sorry to confuse you.:frown:
Could you give a more direct clue how to get the angle DAC?
and i am really sorry.
 
  • #6
Thank you
but i have got it.
 

Related to Problem finding exterior angle

1. What is an exterior angle?

An exterior angle is an angle formed by extending one side of a polygon or geometric figure beyond the vertex. It is measured by the amount of rotation needed to bring the extended side back to its original position.

2. How do you find the exterior angle of a regular polygon?

To find the exterior angle of a regular polygon, you can use the formula 360/n, where n is the number of sides in the polygon. This works because all exterior angles in a regular polygon are equal in measure.

3. Can the exterior angle of a polygon be greater than 180 degrees?

Yes, the exterior angle of a polygon can be greater than 180 degrees. This occurs when the extended side of the polygon makes a full rotation and goes beyond its original position, resulting in an exterior angle that is greater than 180 degrees.

4. How is the exterior angle related to the interior angles of a polygon?

The exterior angle of a polygon is always equal to the sum of the two remote interior angles. This means that the exterior angle and the two remote interior angles form a straight line, or 180 degrees.

5. What is the use of finding exterior angles in geometry?

Finding exterior angles can help in determining the properties and relationships of different shapes and figures. It is also useful in solving problems involving angles, such as finding missing angles in a polygon or calculating the total degrees in a shape.

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