Maths Explained
Enlargements in maths – can anyone please explain to me how you do them?
I have a maths test coming up and this is one of the topics we have to revise. Thanks!
to draw an enlargement, you need to have the point where it’s suppose to enlarge from
then you need to know the factor by which it’s suppose to enlarge by
you multiply that factor by the distance from that point to the corners of your shape.
if the corners of your shape were say 10 cm from the point and the factor was 2, you draw a light line from the point, touching the corner you want to enlarge from and measure 20 cm from the point. The enlarged shape’s new corner is the one you have just found, 20cm away from the point of enlargement. Do this for all the corners, then join up the new corners you have found. This is the enlarged shape of the original. Make sure it looks like the original, because it’s suppose to
If you are using coordinates, you just double the difference in the numbers in the coordinates and add back the respective coordinates of the point. e.g. your point of enlargement is (0,0) and your square has a corner with coordinates (8, 0) and you have a factor of 4. The coordinates for the corresponding corner is = ((8-0)*4+ 0, (0-0)*4+ 0) = (32,0)
Likewise, if the point of enlargement is (1,3) and you have a corner at (2,4), yet you want to enlarge the shape by a factor of 5…((2-1)*5 + 1, (4-3)*5+3), the new coordinates will be (6, 8).
if the scale factor is negative, the maths work fine as it is, you just need to remember the rules for negative numbers
drawing it is a little tricky. If say you want to draw a shape with factor of -3, instead of starting from the point of enlargement, you start from the corner you are working with , let your light line meet the point of enlargement and your measure by 3 times that distance from the corner to the point. Do this for all the corners and join them up. It should look like the shape has been ‘flipped’ over the point onto the other side of the point.
It’s not as complicated as it sounds here, it’s just hard not to have something I can use to illustrate what I am saying. If numbers and buildings appeal to you, this should be easy to get a hang of.
Hope this helps
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