just a quick addition to the great work by Hrish ii above.
Check the picture below.
bearing in mind that twin sides stemming out of a vertex, BD and CD, make twin angles.
Answer:
25°
Explanation:
In
BD = CD .....(Given)
(By isosceles triangle theorem)
Now,
(Angles in linear pair)
Next, in
(By interior angle sum postulate of a triangle)
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