CONTENT

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C.L.I.L.

• CONTENT
• and LANGUAGE
• INTEGRATED
• LEARNING
• You learn content.. MATHS
• You practice language in a specific context..

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Lets talk about. ANGLESWhat is an angle?

• Angle the inclination to one another of two
  straight lines that meet.
• The point at which two lines meet is called the
  vertex of the angle (plural vertices)
• the two straight lines are called sides

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Look at these different types of angles and
remember their names

• Right angle measures 90 degrees
• (its sides are perpendicular)

Straight angle measures 180 degrees (its sides
lie on the same straight line) a straight angle
equals two right angles
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Acute angles measure less than 90 (i.e. less
than a right angle)

• Obtuse angles measure more than 90 but less
  than 180
• (i.e. is greater than a right angle but less
  than a right one)

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• Angles are complementary (or complements of one
  another) if together they equal a right angle.  
• Angles are supplementary (or supplements of one
  another) if together they equal a straight angle
• (a and b are also adjacent)

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TRIANGLES
A triangle is a polygon with three sides and
three angles

• In a triangle
• we use capital letters for the vertices
• we name the opposite side of each vertex with the
  same letter in small letters.
• we name the angles with Greek letters (a, b, g)
  corresponding to the vertices A, B, C

The triangle on the right is the ABC triangle
(e.g. side c is the opposite side of angle g
angles a and b are adjacent to side c)
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Look at these properties of triangles

• there is a connection between the length of the
  sides and the size of the angles
• The side opposite to the bigger angle is
  longer, the same with the small one
• The sum of two sides is always bigger than the
  remaining side
• The three angles always add to 180

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Activity

• Complete
• (refer to ABC triangle)

a lt c ? lt ..
a lt b lt
a b g
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How many types of TRIANGLES?

• There are three special names given to triangles
  that tell how many sides (or angles) are equal
• scalene, isosceles, equilateral
• (? classification of triangles according to
  sides)
• Triangles can also have names that tell you what
  types of angles are inside
• acute, right, obtuse
• (? classification of triangles according to
  angles)

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Types of triangles Types of triangles Types of triangles
By their sides Equilateral triangle A triangle having all three sides of equal length Isosceles triangle A triangle having two sides of the same length Scalene triangle A triangle having all three sides of different length
By their angles Acute triangle A triangle having all acute angles Right triangle (right angled t.) A triangle having a right angle Obtuse Triangle A triangle having an obtuse angle
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Now answer to these questions

• Does a triangle with two obtuse angles exist?
• What is the size of the angles in an equilateral
  triangle?
• If the vertex angle ( the angle which is
  opposite to the base) of an isosceles triangle is
  100, what is the size of the remaining angles?
  How can you classify the triangle in another way?
• d) What type of triangle is the
• grey one?
• Example of answer
• the grey triangle is because it has an
  angle it has also two sides,
  so/therefore it is an triangle

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RIGHT ANGLED TRIANGLES

• The side opposite to the right angle is called
  hypotenuse and it is the longest side
• The other two sides are called legs
• the hypotenuse is
  .
• the legs are
  and
• The inner acute angles add to 90, so they are
  .

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The right angled triangle is one of the most
useful shapes in all of mathematics!

• A right triangle can be isosceles it is called
• isosceles right angled triangle
• ? The size of the acute angles in this type of
  right triangle is always
• (try to explain why)
• We can obtain two equal isosceles right angled
  triangle if we draw a diagonal of a square
• (in another way a square can be divided by a
  diagonal into two isosceles right triangles, that
  are equal
• OR a square is formed by two equal isosceles
  right triangles, joined by the hypoyhenuse)

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Next lessonThe Pythagorean Theorem!!
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NAMING POLYGONS Look at these shapes and find
the right name among those written on the bottom
of the slide
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