year 6 - week 4 - overview

Week 4 Missing angles.notebook

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May 04, 2020

Year 6 - Week 4 - OverviewPlease note that there are questions throughout the teaching slides.

Specific pages for activities and answers are below.


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Lesson 1

WALT: calculate missing angles in a triangle

Write down the name of each type of triangle and everything you can tell me about the angles in the triangle and the length of sides. I have done the first one for you.

Name: Right Angle Triangle

Sides: No equal sides

Angles: One angle is 90

Name:

Sides:

Angles:

Name:

Sides:

Angles:

Name:

Sides:

Angles:


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May 04, 2020Name: Right Angle Triangle

Sides: no equal sides

Angles: one angle is 90

Name: Isosceles

Sides: two equal sides

Angles: two equal angles

Name: Equilateral

Sides: all sides are equal

Angles: all angles are

equal. 60

Name: Scalene or Obtuse triangle

Sides: no equal sides

Angles: no equal angles

(Scalene). One angle bigger

than 90 (obtuse triangle)

Angles inside a triangle add up to 180 . To find a missing angle, we must subtract the angles that we know from 180 .

a

50 Add the angles that you know: 90 + 50 = 140

Subtract from 180: 180 - 140 = 40

Angle a is 40Example 1

a b

c

51

Isosceles triangles have to equal angles.

Angle a is 51 , so angle b is 51 .

Add the angles up. 51 +51 = 102

Subtract them from 180:

180 - 102 = 78

Angle c = 78

Sometimes it might look like this.e

f

d

Angles e and f are the same.

Angle d = 46

Subtract this from 180: 180 -46 = 134

This means e+f =134

So divide 134 by 2.

d = 46 e = 67 f = 67


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Right Angle Triangles:

Isosceles Triangles:

Scalene Triangles


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We also know that angles on a straight line add up to 180 and angles round a point add up to 360 . Use this knowledge to find the missing angles in this question:


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Answers


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We also need to remember that angles on intersecting lines are equal.

The lines are like a pair of scissors.

a

b

c

d

Angles a and c are equal.

Angles b and d are equal.

To answer this question, first you would need to find out what angle z is.

Remember, add the angles together, and then subtract them from 180.


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Practise


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Stretch


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Stretch continued


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May 04, 2020

Challenge


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May 04, 2020

Challenge continued


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Practise answers Stretch answers


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Challenge answers


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Lesson 2

WALT: calculate angles in quadrilaterals

Can you name these quadrilaterals?

These lines tell us which sides are the same length.


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A parallelogram has two sets of equal sides.

They are marked with lines like this or

Angles inside a quadrilateral add up to 360.

75

75105To find the missing angle, we need to add up the angles that we know and subtract the total from 360. 105+75+75 =255

360 - 255 = 105.


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Use your knowledge of these quadrilaterals to find the missing angles and sides.


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Answers

4cm 90

907cm

104

110

115

6cm

122

3cm


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Practise


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Stretch

Can you write a sentence to explain your reasoning?


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Challenge

1a


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Practise Answers


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Stretch Answer


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May 04, 2020

Challenge Answers

1a


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Lesson 3

WALT: calculate angles in polygons

What is a polygon?A polygon is any 2D shape that has 3 sides or more. These shapes are all polygons.

Regular polygons have: more than 3 sides, all angles are equal and all sides are equal length. For example, this octagon:

An irregular polygon will have different length sides and different angles.

For example, this irregular pentagon:


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A polygon can be partitioned into triangles in order to calculate the total of the interior angles inside the shape. The sum of the angles in a triangle is 180°.

This quadrilateral can be partitioned into 2 triangles.2 × 180° = 360°

What is the name of this polygon?

How many triangles can this polygon be partitioned into?

How will this help you calculate the sum of the interior angles inside the shape?


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May 04, 2020

What is the name of this polygon?Hexagon

How many triangles can this polygon be partitioned into?A hexagon can be partitioned into 4 triangles.

How will this help you calculate the sum of the interior angles inside the shape?4 × 180° = 720°The sum of interior angles in a hexagon = 720°.

180

180

180

180

Try this question


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This is why it is important to start at one vertex (corner) and come back to that vertex each time. I like to start at the bottom left hand corner (if that is possible).

Answer

Try this one:


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Answer The octagon has been partitioned into 6 triangles.

Interior angles = 1080

Divide by 8 because there are 8 interior angles in an octagon.

Angles on a straight line = 180


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Practice


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Stretch


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May 04, 2020

Challenge


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May 04, 2020

Pracitse Answers

Stretch Answer


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May 04, 2020

Challenge Answers


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Lesson 4

MymathsThink carefully about how you have done in your activites this week before you choose Pracitse, Stretch or Challenge. Please do not focus on what year group Mymaths has set the activity as. The activities relate to all the areas we have covered this week.

Activites are set for Thursday 14th May.

Practise: Properties of triangles. Some of you have already completed this activity, but not all of you. If you have not previously done this activity please do it, and then move onto Stretch if you feel confident.

Stretch: Angle reasoning.

Challenge: Sum of angles in polygons. This is challenging, but some of you will be capable of completing it.


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Lesson 5

Problem Solving

It was lovely to hear that so many of you are enjoying the problem solving activites that I have set. So here is one more!

Let's share our answers on our Zoom chat on Tuesday 19th May.

year 6 - week 4 - overview

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