The angles of a triangle are in A.P., and the number of degrees in the least angle is to the number of degrees in the mean angle as 1:120. Find the angle in radians.

Let the angles of the triangle be (a – d) °, a° and (a + d) °.


We know that the sum of the angles of a triangle is 180°.


a – d + a + a + d = 180°


3a = 180°


a = 60°


Given





120 – 2d = 1


2d = 119


d = 59.5


Hence, angles are:


(a – d) ° = 60° – 59.5° = 0.5°


a° = 60°


(a + d) ° = 60° + 59.5° = 119.5°


Angles of triangle in radians:





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