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Posts tagged with scale factor

June23

There are some quite complicated and unnecessary complexities with Similar Triangles for some students. Let’s try and keep it simple. Look at the two triangles below. They look similar but, first, what do we mean by “Similar”? Similar means that one triangle is an enlargement of another. In other words, one triangle has been scaled […]

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Enlargement (or Dilation) with a great app

March11

There is a good app from waldomathsÂ (Java required) to see what happens when we have scale factors that are positive, zero and negative. For example, what would the image of a shape look like if it is enlarged by a scale factor of -3 rather than +3 ??               […]

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Scale – the Mathematics of Supersizing without Fries

March11

In this picture it seems that the golf ball is enlarged too much for our budding maths student!! There are two ways to look at scale – one is that similar objects (that is, objects which have corresponding angles the same) also have their corresponding sides in the same ratio. For example, say we have […]

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Post Support

NCEA Level 2 Algebra Problem. Using the information given, the shaded area = 9, that is:
y(y-8) = 9 –> y.y – 8y – 9 =0
–> (y-9)(y+1) = 0, therefore y = 9 (can’t have a distance of – 1 for the other solution for y)
Using the top and bottom of the rectangle,
x = (y-8)(y+2) = (9-8)(9+2) = 11
but, the left side = (x-4) = 11-4 = 7, but rhs = y+? = 9+?, which is greater than the value of the opp. side??
[I think that the left had side was a mistake and should have read (x+4)?]