the vertical angle of an isosceles triangle is 100 degree.find its base angles.
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Given : In ∆ABC ,
AB = AC ,
vertical angle <A = 100°
<C = <B ---( 1 )
[ Angles opposite to equal
sides are equal ]
Now ,
<A + <B + <C = 180°
[ Angle sum property ]
100° + <B + <B = 180° [ From ( 1 ) ]
=>2 <B = 180° - 100°
=> 2<B = 80°
=> <B = 80/2 = 40°
Therefore ,
<B = <C = 40°
•••••
AB = AC ,
vertical angle <A = 100°
<C = <B ---( 1 )
[ Angles opposite to equal
sides are equal ]
Now ,
<A + <B + <C = 180°
[ Angle sum property ]
100° + <B + <B = 180° [ From ( 1 ) ]
=>2 <B = 180° - 100°
=> 2<B = 80°
=> <B = 80/2 = 40°
Therefore ,
<B = <C = 40°
•••••
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