Year 8

# Finding missing angles in polygons

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## Lesson details

### Key learning points

- In this lesson, we will learn how to find an unknown angle in a polygon.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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### 5 Questions

Q1.

If I split a 7 sided shape into 5 triangles, I have done the correct process to find the total interior angles within the shape.

False

Q2.

Which of the following WOULD give you the total interior angles within a n-sided polygon?

180n

360n

360n - 180

Q3.

Which of the following WOULD NOT give you the total interior angles of a n-sided polygon?

180(n - 2)

180n - 360

Q4.

The sum of the total interior angles in a 30 sided shape is...

504 degrees

540 degrees

5400 degrees

Q5.

What would be the correct calculation to work out the total sum of the interior angles in a decagon?

180(10)

360(10-2)

360(8)

### 5 Questions

Q1.

A triangle is made up of the following: 73 degrees, 51 degrees and x degrees. Solve for x.

180 degrees

236 degrees

65 degrees

Q2.

If a quadrilateral contains 3 right angles, what must the final angle be to form a quadrilateral?

A reflex angle

An acute angle

An obtuse angle

Q3.

If the angles in a decagon are the following: 73 degrees, 293 degrees, 203 degrees, 9 degrees, 29 degrees, 184 degrees, 173 degrees, 93 degrees, 208 degrees, y degrees. Solve for y.

295

75

95

Q4.

Is it possible to have two obtuse angles in a triangle?

Yes

Q5.

You are told that V + W + X + Y + Z = total interior sum of a pentagon. If V = 90 degrees, W = 110 degrees, X = 10 degrees, Y = 300 degrees, what would Z be?

210

3

300