No. 1 A 90 2 = 45 180 - 45 45 = 135 (180 - 45 ) 2 = 67.5 - - PowerPoint PPT Presentation

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Mar 05, 2023 105 likes •476 views

No. 1 A 90 2 = 45 180 - 45 45 = 135 (180 - 45 ) 2 = 67.5 180 - 90 - 45 B = 45 90 90 E C F 90 67.5 - 22.5 180 - 90 - 67.5 = 45 = 22.5 D 67.5

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No. 1

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A B C D E F

90 90 90 45 90 ÷ 2 = 45

(180- 45) ÷ 2 = 67.5 180- 90- 67.5 = 22.5

67.5

67.5 - 22.5 = 45 180 - 90 - 45 = 45 180 - 45 = 135

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Isosceles triangle Can you name this shape?

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 What can you tell me about the

isosceles triangle?

 Look at the sides and angles.  What about lines of symmetry?  Will it tessellate?  What shapes can you make

with 1, 2, 3, or more of these shapes?

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In an isosceles triangle, there are two equal sides. In an isosceles triangle, there are two equal angles.

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What shapes can you make with 1, 2, 3, or more of these shapes? Isosceles triangle

An isosceles triangle can tessellate.

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How many lines of symmetry are there in an isosceles triangle?

1

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Log onto Nearpod.com

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In the figure, not drawn to scale, AB=AC. Find ABC.

A C B

80°

 ABC=  ACB

   

50 2 100 2 80 180    

Sum of angles of a triangle is 180°.

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No. 2

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Right-angled triangle Can you name this shape?

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 What can you tell me about this

right-angled triangle?

 Look at the sides and angles.  What about lines of symmetry?  Will it tessellate?  What shapes can you make with 1,

2, 3, or more of these shapes?

Right-angled triangle

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How many lines of symmetry are there in this triangle?

1

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What shapes can you make with 1, 2, 3, or more of these shapes?

A right- angled triangle can tessellate.

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EFG is a right-angled triangle. EGI is a straight line and GHI is an isosceles triangle. Find FGH. F E G H I 52 70 64 64

FGE=180 - 90 - 70  = 20

20 FGH=180 - 20 - 64 = 96

96

        64 2 52

HIG HGI

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No. 3

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Equilateral triangle Can you name this shape?

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What is special about an equilateral triangle?

 What can you tell me about an

equilateral triangle?

 Look at the sides and angles.  What about lines of symmetry?  Will it tessellate?  What shapes can you make with 1, 2,

3, or more of these shapes?

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How many lines of symmetry are there in an equilateral triangle ?

3

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In an equilateral triangle, there are three equal sides.

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In an equilateral triangle, the three angles are equal. a b c a +  b + c = 180 °  a =  b =  c =180°÷ °÷3 = 60 °

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ABCD is a square. QM=QP=QN. MN is perpendicular to PQ. Find MPN A B C D P M N Q MQN=1803=60 MQP=602=30 30 Triangle MQP is an isosceles triangle.      75 2 30 180 MPQ MPN=752=150 Since, given that QM=QP=QN= MN Therefore triangle MNQ is an equilateral triangle.

150

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