Dear student,

In any triangle ,sum of angles in a triangle is pie

Now the two angles in radians are given as : 5pie/9 and 5pie/18.

Therefore the third angle (in radians) will be :- (pie) - 5pie/9 - 5pie/18 = pie/6

Therefore the third angle is = pie/6 rad

And,

third angle in degrees will be = (pie/6) × (180/pie) = 30 degrees