Grade 10 Maths · Euclidean Geometry

Use angle sum of a polygon

Find angles in a polygon using the fact that the inside angles add up to 180(n − 2)° (for example a quadrilateral's angles add up to 360°).

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Interior Angles of a Polygon - GeometryThe Organic Chemistry Tutor

Finding the Missing Angle of a QuadrilateralMath with Mr. J

How To Calculate The Interior Angles and Exterior Angles of a Regular PolygonThe Organic Chemistry Tutor

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Question 5.1 · March 2021 · Provincial · 2 marks

5.1 The angles of a certain quadrilateral are in the ratio 2:3:4:6. Calculate the size of the largest angle.(2)

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3. Question WE11.12 · Siyavula Grade 8 Mathematics, 11 Geometry of 2D shapes, Classifying quadrilaterals, Worked example 11.12 · 4 marks
$Diagram for this question$
WE11.12 $A BC D$ is a kite with $\hat{A} = 2 z + 16°$ , $\hat{D} = 103°$ , $\hat{C} = z$ , $A D = A B$ and $C D = CB$ . Find the value of $z$ .(4)
Show the memo (4 ticks)Memo
1. ✓
  Angle B $\hat{D} = \hat{B} = 103°$ (opp. $∠$ s equal)
  1 mark · Use properties of quadrilaterals
2. ✓
  S: angle sum equation $\hat{A} + \hat{B} + \hat{C} + \hat{D} = 360°$
  $2 z + 16° + 103° + z + 103° = 360°$
  1 mark · Use angle sum of a polygon
3. ✓
  R: sum of angles of a quadrilateral(sum of $∠$ s quad.)
  1 mark · Use angle sum of a polygon
4. ✓
  Answer $3 z = 360° - 222°$
  $3 z = 138°$
  $∴ z = 46°$
  1 mark · Use angle sum of a polygon

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