Question

(a) in the given triangle ABC if angleACD is 120° and angel B = 50 then find rest angle of ABC.
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Answer 1

Answer:

∵AB=AC⇒∠ABC=∠ACB=x(say)

Let ∠BAC=y

We know,

Exterior angles = sun of interior opposite angles

or, 120

o

=∠ABC+∠BAC

or, 120

o

=x+y−−−(1)

Again, ∠ACB+∠ACD=180

o

or, x+120

o

=180

o

∴

x=60

o

From (1),

60

o

+y=120

o

⇒

y=60

o

∴

∠A=60

o

Step-by-step explanation:

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Answer 2

Answer:

AB=AC⇒∠ABC=∠ACB=x(say)

Let ∠BAC=y

We know,

Exterior angles = sun of interior opposite angles

or, 120

o

=∠ABC+∠BAC

or, 120

o

=x+y−−−(1)

Again, ∠ACB+∠ACD=180

o

or, x+120

o

=180

o

∴

x=60

o

From (1),

60

o

+y=120

o

⇒

y=60

o

∴

∠A=60

o

solution