Q.In triangle △ABC, ∠ABC = 90° and BD ⊥ AC. If AB = 5 cm and BC = 12 cm, then what is the length of BD?

In right-angled triangle \(\triangle\)ABC: \(AC = \sqrt{AB^2 + BC^2} = \sqrt{5^2 + 12^2}\) cm = 13 cm Again, from the right-angled vertex B, BD is drawn perpendicular to the hypotenuse AC. \(\therefore\) Triangles \(\triangle\)ABC and \(\triangle\)ADB are similar. \(\therefore \cfrac{AC}{AB} = \cfrac{BC}{BD}\) i.e., \(BD = \cfrac{AB \times BC}{AC} = \cfrac{5 \times 12}{13}\) cm = \(\cfrac{60}{13}\) cm = \(4\cfrac{8}{13}\) cm. (Answer)
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