In Δ ABC, AB = 12 cm, BC = 16 cm and AC = 20 cm. A circle is inscribed inside the triangle. What is the radius (in cm) of the circle? 

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AAI Junior Assistant (Fire Service) Official Paper (Held On: 15 Nov 2022 Shift 1)
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Answer (Detailed Solution Below)

Option 2 : 4
Free
ST 1: English
20 Qs. 20 Marks 25 Mins

Detailed Solution

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Given:

In Δ ABC, AB = 12 cm, BC = 16 cm, AC = 20 cm

Formula used:

Area of the triangle (Δ) =

Where s = semi-perimeter =

Radius (r) of the inscribed circle =

Calculations:

a = 12 cm, b = 16 cm, c = 20 cm

s =  = 24 cm

Area (Δ) = 

⇒ Area (Δ) = 

⇒ Area (Δ) = 

⇒ Area (Δ) = 96 cm2

Radius (r) = 

⇒ Radius (r) = 4 cm

∴ The correct answer is option (2).

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