Question

Three angles of a triangle are in arithmetic progression with a common difference of 20 degrees. what is the smallest angle in that triangle?

Answer 1

three angles
sum of angles become

a + a + d + a + 2d= 180. [d=20 given]
3a +3d=180
3a + 60 = 180
3a = 120
a= 40

angles become
a= 40°
a+d = 60°
a + 2d= 80°

so the smallest angle is 40°

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