Question

A triangle ABC is enlarged, about the point O as centre of enlargement, and the scale factor is 3. Find BC. if B'C'= 15 cm.

• A. 6 cm
• B. 5 cm
• C. 7 cm
• D. none of the above

Answer 1

The correct option is B 5 cm

$△ABC$ is enlarged to $△A^{\prime }{B}^{\prime }{C}^{\prime }$,
Thus, $\frac{B^{\prime }{C}^{\prime }}{BC}=3$
$\Rightarrow \frac{B^{\prime }{C}^{\prime }}{BC}=3$
$\Rightarrow BC=\frac{15}{3}$
$\Rightarrow BC=5$ cm