Question

The sum of seven of an angle of a decagon is 11700. The other three angles are all equal to each other. Calculate the sizes of the other three angles.

Answer 1

sum of angles of decagon =

$((n - 2) \times 180) \\ ((10 - 2) \times 180) \\ 8 \times 180 = 1440$

let the three equal angles be x,x,x

A/Q

$1170 + 3x = 1440 \\ 3x = 270 \\ x = 90$

Size of other equal angles= 90,90,90