1.

Find the inradius (approximate value) of the triangle having sides 12 cm, 16 cm and 22 cm.1. 3.7 cm2. 6.7 cm3.1.5 cm4. 7.3 cm

Answer» Correct Answer - Option 1 : 3.7 cm

Given:

Sides of triangles are 12 cm, 16 cm, and 22 cm

Formula used:

Area of triangle = \(\sqrt {s\left( {s\; - \;a} \right)\left( {s\; - \;b} \right)\left( {s\; - \;c} \right)} \)

Here, s is semi perimeter, and a, b, and c are sides of the triangle

Inradius = Area/s

Calculation:

Let a be 12 cm, b be 16 cm, and c be 22 cm

Semi perimeter (s) = (12 + 16 + 22)/2

⇒ s = 50/2 = 25

Area of triangle = \(\sqrt {s\left( {s\; - \;a} \right)\left( {s\; - \;b} \right)\left( {s\; - \;c} \right)} \)

⇒ Area of triangle = \(\sqrt {25\left( {25\; - \;12} \right)\left( {25\; - \;16} \right)\left( {25\; - \;22} \right)} \)

⇒ Area of triangle = \(\sqrt {25 \times 13 \times 9 \times 3} \)

⇒ Area of triangle = √8775 cm2

⇒ Area of triangle ≈ 93.67

Inradius = Area/s

⇒ Inradius = 93.67/25

Inradius is 3.7 cm approximately



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