Answer:
The above triangle is an isosceles triangle....
Reason
As we can see AB and DE are parallel to each other
As angle ABC is 80 degree
Therefore BCE is too 80 degree (as they both are alternate to each others)
Hence angle DCB is a 50 degree because in the straight DCE we have angle BCE as 80 degree and Angle ACD as 50 degree
Since a straight line has 180 degree therefore the remaining angle ACB is 50 degree(180-80-50)
Now in triangle BAC. Angle C is 50 degree and Angle B is 80 degree, since the total angle of a triangle is 180 degree therefore A is 50 degree that is angle BAC is 50 degree(180-50-80) .
Hence here we see that two opposite sides have same angle that is the reason its a ISOSCELES triangle
Answer BY AN INDIAN
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