Q3 of 59 Page 195

The measurement of four angles of a pentagon are 65°, 89°, 132°, 116° respectively. Let’s write the measurement of the fifth angle.

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°.


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