The measurement o

Now for a pentagon, we know it has five sides. So let us substitute n = 5 in the formula.

Sum of interior angles is given as = (2 × 5 – 4) × 90

= (10 – 4) × 90

= 6 × 90

= 540°

Let the fifth angle be x.

Now let us add all the angles.

65 + 89 + 132 + 116 + x = 540

402 + x = 540

x = 540 – 402

x = 138°.