An irregular polygon has external angles as 140,120,142,132,112and a.

sure they are not internal??

If so, note that there are 7 angles, so also seven sides.

The sum of the interior angles of a 7-gon is (7-2)*180 = 900
Now you can find a.

To find the value of angle a in the irregular polygon, we can use the fact that the sum of the exterior angles of any polygon is always 360 degrees.

So, let's add up all the known exterior angles: 140 + 120 + 142 + 132 + 112 = 646 degrees.

Now, subtract this sum from 360 to find the remaining angle:

360 - 646 = -286 degrees

However, angles in a polygon cannot be negative, so we need to make them positive by adding 360 degrees:

-286 + 360 = 74 degrees

Therefore, the value of angle a is 74 degrees.