In Fig. 10, triangle ABC is an isosceles triangle where AB = AC. BO and CO are the bisectors of ZABC and ZACB respectively. Find the value of the angles of triangle ABC.
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Answers
Step-by-step explanation:
In ΔABC
AB=AC
∠ACB=∠ABC
2
1
∠ACB=
2
1
∠ABC
∠OCB=∠OBC
in ΔBOC
∠OBC+∠OCB+∠BDC=180
∘
2∠OBC+∠BOC=180
∘
∠ABC+∠BOC=180
∘
∠ABC+∠OBA=180
∘
∠DBA=∠BOC
Step-by-step explanation:
Given :-
∆ABC is an isosceles triangle where AB = AC. BO and CO are the bisectors of <ABC and <ACB respectively.
To find :-
Find the value of the angles of triangle ABC?
Solution :-
Given that
In∆ABC is an isosceles triangle ,AB = AC.
=> <ABC = <ACB
Since The angles opposite to the equal sides are equal.
Let <ABC = <ACB = X°
Now,
BO and CO are the bisectors of <ABC and <ACB
=> <ABC= <ABO+<OBC
and
<ABO= <OBC = <ABC /2 = X°/2
and
<ACB = <ACO + <OCB
and
<ACO = <OCB=<ACB /2 = X°/2
Now,
In ∆ OBC ,
<OBC + <BOC+ <BCO = 180°
Since The sum of all angles in a triangle is 180°
=> (X°/2)+100°+(X°/2) = 180°
=> (2X°/2)+100° = 180°
=> X° = 180°-100°
=> X° = 80°
=> <ABC = <ACB = 80°
Now
Now,
In ∆ABC,
<ABC + <BCA+ <CAB = 180°
Since The sum of all angles in a triangle is 180°
=> 80°+<BAC+80°= 180°
=> <BAC+160° = 180°
=> <BAC = 180°-160°
=> <BAC = 20°
Therefore,<ABC = <ACB = 80° and <BAC = 20°
Answer:-
The angles of the triangle are 20° ,80° and 80°
Used formulae:-
→ The sum of all angles in a triangle is 180°
→The angles opposite to the equal sides are equal.