Home / iGCSE Mathematics (0580) – C4.4 Similarity- Exam Style Questions Paper 1

iGCSE Mathematics (0580) - C4.4 Similarity- Exam Style Questions Paper 1- New Syllabus

Question

Rectangle $A$ is mathematically similar to rectangle $B$.

Work out the value of $x$.

Most-appropriate topic codes (Cambridge IGCSE Mathematics 0580):

C4.4 Similarity
▶️ Answer/Explanation

Since the rectangles are mathematically similar, the ratio of their corresponding sides is exactly the same. We can find the linear scale factor from rectangle $B$ to rectangle $A$: $$\text{Scale Factor} = \frac{\text{Length of } A}{\text{Length of } B} = \frac{8}{2} = 4$$ This means rectangle $A$ is 4 times larger in every dimension. We apply this factor to the width: $$x = 1.5 \times 4 = 6$$

Answer: $x =$ 6

Question

Triangle $ABC$ is mathematically similar to triangle $PQR$. Given $AB=5\text{ cm}$, $BC=7\text{ cm}$, and $PQ=10\text{ cm}$, show that $QR = 14\text{ cm}$.

Most-appropriate topic codes (Cambridge IGCSE Mathematics 0580):

C4.4 Similarity
▶️ Answer/Explanation
Since the triangles are mathematically similar, their corresponding sides are proportional. We find the scale factor by dividing the known side of the larger triangle by its corresponding side on the smaller triangle: $\text{Scale Factor} = \frac{PQ}{AB} = \frac{10}{5} = 2$. Multiplying the corresponding side $BC$ by this scale factor gives $QR = 7 \times 2 = 14\text{ cm}$.
Answer: $\frac{10}{5} \times 7 = 14$
Question

Shape A is mathematically similar to shape B.

Calculate the value of x.

▶️ Answer/Explanation
Solution

Ans: 8 cm

Find the scale factor: 6.75 ÷ 2.7 = 2.5

Apply to the other side: x = 3.2 × 2.5

Calculate: x = 8 cm

Alternatively: 3.2/x = 2.7/6.75 → x = (3.2 × 6.75)/2.7 = 8

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