Enlargement by rational scale factorsIB MYP Maths Extended: Flashcards

What these 13 flashcards ask

What two things describe an enlargement?
What happens to angles in an enlargement?
Effect of a scale factor between 0 and 1?
Effect of a negative scale factor?
Image of (4,-6): centre O, k=\frac12?
Image of (4,-6): centre O, k=-\frac12?
Formula for the image of P with centre C and scale factor k?
How do you find the centre of an enlargement?
Lengths are multiplied by what?
Areas are multiplied by what?
Volumes are multiplied by what?
A shape of area 12 is enlarged with k=\frac12. New area?
A model has k=\frac1{20}. Statue volume 21 m^3. Model volume?

Exam questions on Enlargement by rational scale factors

Triangle $ABC$ has vertices $A(2,2)$ , $B(6,2)$ and $C(6,8)$ . It is enlarged with centre the origin $O$ and scale factor $\frac12$ to give triangle $A'B'C'$ .
Triangle $A''B''C''$ is the image of $ABC$ under an enlargement with centre $O$ and scale factor $-\frac12$ . Find the coordinates of $B''$ .2 marks
Triangle $T$ has vertices $(2,1)$ , $(3,1)$ and $(3,3)$ . Triangle $T'$ has vertices $(-1,1)$ , $(-3,1)$ and $(-3,-3)$ . $T'$ is the image of $T$ under a single enlargement.
A different shape of area 5 cm $^2$ is enlarged by the same enlargement (the same centre and scale factor). Find the area of its image.2 marks
A sculptor makes a clay model of a statue. The model is an enlargement of the statue with scale factor $\frac{1}{20}$ . The statue is 6 m high, has a surface area of 48 m $^2$ and a volume of 21 m $^3$ .
Find the height of the model in centimetres and the surface area of the model in cm $^2$ .3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).