In a triangle ABC, angle B = 90° and p is the length of the perpendicular from B to AC. If BC = 10 cm and AC = 12 cm, then what is the value of p?

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CDS Elementary Mathematics 3 Sep 2023 Official Paper
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  1. \( \frac{5 \sqrt{11}}{3}\)
  2. \(\frac{10 \sqrt{11}}{3} \)
  3. \( \frac{40}{\sqrt{61}} \)
  4. \( \frac{12}{25}\)

Answer (Detailed Solution Below)

Option 1 : \( \frac{5 \sqrt{11}}{3}\)
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Detailed Solution

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Given:

ABC is right angle triangle at angle B, BC = 10 cm

 AC = 12 cm, p is length of the perpendicular from B to AC

Formula used:

ArΔ = 1/2 × base × height

Calculation:

F1 Vinanti Defence 01.12.23 D9

In an Δ ABC, by using the Pythagoras theorem

AC2 = AB2 + BC2

144 = AB2 + 100

AB2 = 44

AB = √44

Here, We can find the area in two ways,

1) By taking AC as the base & length p as the perpendicular.

2) By taking BC as base & AB as the perpendicular

As, Area (ΔABC) = Area (ΔABC)

⇒ 1/2 × 10 × √44 = 1/2 × 12 × p

⇒ 5 × 2√11 = 6p

⇒ p = (5√11)/3 cm

∴ The correct answer is (5√11)/3 cm

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