Question

the four angle of quadrilater form an ap if the sum of the first 3 angle is twice the the fourth angle find the all angle

Answer 1

Let sum of all the 3 angles be 2x
and,
4th angle be x ,
then,  
2x+x=360 (angle sum property of a quadrilateral)
3x=360
x=360/3
x=120
so,
4th angle is 120
and the rest are 2x=2*120=240,
still there are 3 angles left so,
3x=240
x=240/3
x=80
so rest 3 angles are each of 80 degrees.