Problem solving with similarity
I can use my knowledge of similarity to solve problems.
Problem solving with similarity
I can use my knowledge of similarity to solve problems.
Lesson details
Key learning points
- A scaled version of a shape is very useful.
- Being able to scale the perimeter can reduce the number of calculations.
- Enlargement (transformations) and similar shapes are connected.
Common misconception
A ratio of 1 : 400 for a scale model of a car to a real car will have units of cm and metres, because a scale model is measured in cm and a real car is measured in metres.
Unless the scale explicitly includes different units of measure for each part, you must always use the same unit for each part of a ratio. So, 1 : 400 should be seen as 1 cm : 400 cm, not 400 metres, which is far too long for a car!
Keywords
Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.
Invariant - A property of a shape is invariant if that property has not changed after the shape is transformed.
Enlargement - Enlargement is a transformation that causes a change of size.
Scale factor - A scale factor is the multiplier between similar shapes that describes how large one shape is compared to the other.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
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Starter quiz
6 Questions
a -
∠ABC
b -
hypotenuse
c -
adjacent
d -
RHS
Exit quiz
6 Questions
