SSC CGL 2022 PYQ — Question 29

SSC CGL Tier II - Quant - 3 Feb 2022 • Quantitative Aptitude • Q29

Three sides of a triangle are a2+b2,(2a)2+b2\sqrt{a^2+b^2}, \sqrt{(2a)^2+b^2} and a2+(2b)2\sqrt{a^2+(2b)^2} units. What is the area (in unit squares) of the triangle?

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 32\frac{3}{2} ab

Here we don't know anything about the values of a and b so let's suppose,

a = b then the respective sides become,

a2+b2=a2+a2=2a\sqrt{a^2 + b^2} = \sqrt{a^2 + a^2} = \sqrt2a

(2a)2+b2=4a2+a2=5a\sqrt{(2a)^2 + b^2} = \sqrt{4a^2 + a^2} = \sqrt5a

a2+(2b)2=a2+4a2=5a\sqrt{a^2 + (2b)^2} = \sqrt{a^2 + 4a^2} = \sqrt5a

Now one can say that the triangle must be an isosceles triangle.

Area of an isosceles triangle = b4×4a2−b2\frac{b}{4} \times \sqrt{4a^2 - b^2}

2a4×4×(5a)2−(2a)2\frac{\sqrt2 a}{4} \times \sqrt{4 \times (\sqrt5a)^2 - (\sqrt2a)^2}

= 3/2 × a2 = 3/2 ab.