∠72
Step-by-step explanation:
- It is isosceles Triangle.
Therefore Two sides will be equal
∠b = ∠c ------ ☆
- Given in the question - Angle b is twice the angle a.
=> ∠b = 2∠a
=> ∠a = ∠b/2 -------(1)
- sum of two sides on isosceles Triangle is 180°
=> ∠a + ∠b + ∠c = 180
Put value of ∠a from equation (1)
=> ∠b/2 + ∠b + ∠b =180
[ look equation marked - ☆ ]
=> 5∠b/2 = 180
=> 5∠b = 180 × 2
=> 5∠b = 360
=> ∠b = 360 / 5
=> 72
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Some properties of Triangle-
- two sides are equal.
- two internal angles are equal.
- two angles are opposite to equal side are equal.
- sum of two angles 180°
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