Question

Here is a pentagon work out the value y.

Answer 1

125°

Explanation:

First you find the value of total interior angles

Since it's a Pentagon

`(5- 2) * 180`

Then you arrive at 540°

When you sum all the angles in the Pentagon together they should be equal to 540

`540 = 86 + 142 + 72 + 115 + y`

`540 = 415 + y`

`540 - 415 = y`

`y = 125`

Answer 2

y = 125°

Explanation:

the sum of the interior angles of a polygon is

sum = 180° (n - 2) ← n is the number of sides

here n = 5 , then

sum = 180° × (5 - 2) = 180° × 3 = 540°

sum the interior angles and equate to 540°

y + 86° + 142° + 72° + 115° = 540°

y + 415° = 540° ( subtract 415° from both sides )

y = 125°