What is the area of the triangle ABC with sides a = 10cm  and c = 4cm angle B = 30°?

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NDA (Held On: 18 Apr 2021) Maths Previous Year paper
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  1. 16 cm2
  2. 12 cm2
  3. 10 cm2
  4. 8 cm2

Answer (Detailed Solution Below)

Option 3 : 10 cm2
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Detailed Solution

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Concept:

Area of a triangle = \(1\over 2\) × base × altitude

Area of ΔABC = \(\rm {1\over2} (a \cdot b\cdot sin \ C)\)

F1 Aman kumar Shraddha 05.05.2021. D9

 

Calculation:

Area of a triangle = \(1\over 2\) × base × altitude

\(1\over 2\) × c × a sin∠CBA

\(1\over 2\) × 10 cm × 4cm sin 30° 

= 5 × 4 × \(1\over 2\) (as sin 30° = \(1\over 2\))

= 10 cm2

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