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In triangle ABC, the angles are such that angle B is 20° more than angle A, and angle C is 40° more than angle A.
Find angle A.

Class 9Angle Sum of a TriangleGeometry — Lines and Angles

A80
B36
C44
D40

Step-by-Step Solution

Let angle

A = a

. Then

a + (a + 20) + (a + 40) = 180

, so

3 a + 60 = 180, 3 a = 120, a = 40

deg.

Answer: D) 40

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