Question

Mark (✓) against the correct answer
∆ABC is right-angled at A. If AB = 24 cm and AC = 7 cm then BC = ?

(a) 31 cm
(b) 17 cm
(c) 25 cm
(d) 28 cm

Answer 1

$$\begin{gathered} \left(\mathrm{c}\right)25\mathrm{cm} \\ \begin{array}{l}\text{In a right angle triangle ABC:}\\ {\text{AC}}^2={\text{BC}}^2+{\text{AB}}^2\\ {\text{=>BC}}^2={24}^2+7^2\\ {\text{=>BC}}^2\text{=}576+49\\ {\text{=>BC}}^2=625\\ \text{=>BC}=\pm 25\text{cm}\end{array} \\ \mathrm{Since}\mathrm{the}\mathrm{length}\mathrm{cannot}\mathrm{be}\mathrm{negative},\mathrm{we}\mathrm{will}\mathrm{negelect}-25. \\ \therefore \mathrm{BC}=25\mathrm{cm} \end{gathered}$$