# in a triangle ABC, BC=AB and angle B=80 degrees, Then find the measure of angle A

Dear Students,

Given : BC = AB

$⇒$$\angle$A = $\angle$C                 ................ (1)   (Angle opposite to equal sides are equal)
Now,
$⇒$$\angle$A + $\angle$B + $\angle$C = 180             (Angle Sum property)
$⇒$$\angle$A + 80 + $\angle$A = 180             (From (1))
$⇒$$\angle$A = 180 - 80
$⇒$$\angle$A = 100
$⇒$$\angle$A = 50

Regards

• 17
sorry
• -4
50° is Angle A
• 1
The theorem used here is Opposite sides are if equal then their opposite angles will also be equal....So here we proved Angle A = Angle C Using Angle sum property Angle A+Angle B+Angle C =180° Angle A+Angle C =100° 2(Angle A)=100°. [PROVED EARLIER] Angle A = 50°
• 2
50 is the measure of Angle A
• 0
Angle A= 50.
• 1
angle a =500
• -1
Thanq very much
• 0
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