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25 votes
Lie on a strought

A B and c
line
A
B
BO=CD
LBC D = 60 and LBADS
out X
work

Lie on a strought A B and c line A B BO=CD LBC D = 60 and LBADS out X work-example-1
User Dellowar
by
5.5k points

2 Answers

8 votes

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.

Lie on a strought A B and c line A B BO=CD LBC D = 60 and LBADS out X work-example-1
User DMH
by
5.4k points
13 votes

Answer:

25°

Explanation:

In
\triangle BCD

BD = CD .....(Given)


\implies m\angle CBD = m\angle BCD

(By isosceles triangle theorem)


m\angle BCD = 60\degree....(given)


\implies m\angle CBD = 60\degree

Now,


m\angle CBD + m\angle ABD= 180\degree

(Angles in linear pair)


\implies 60\degree + m\angle ABD= 180\degree


\implies m\angle ABD= 180\degree - 60\degree


\implies m\angle ABD= 120\degree

Next, in
\triangle ABD


m\angle BAD + m\angle ABD+ m\angle ADB= 180\degree

(By interior angle sum postulate of a triangle)


\implies 35\degree + 120\degree+ x= 180\degree


\implies 155\degree+ x= 180\degree


\implies x= 180\degree-155\degree


\implies x= 25\degree

User Karthika PB
by
4.1k points