Six angles of a heptagon measure 107, 139, 131,110, 145 and 128 what is the measure of the seventh angle?

1 Answer
May 9, 2018

#7^(th)# angle is #140^@#

Explanation:

Sum of all the angles of a polygon of #n# sides is

#(n-2)xx180^@#

As a heptagon has #7# sides sum of its angles is

#(7-2)xx180^@=5xx180^@=900^@#

Now six angles add up to

#107^@+139^@+131^@+110^@+145^@+128^@=760^@#

Hence #7^(th)# angle is #900^@-760^@=140^@#