Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Mensuration: 2D

Question:

Three circles of equal radius 'r' cm touch each other.  The area of shaded region is?

Options:

(\(\frac{\sqrt {3}+π}{2}\)) r2 sq. cm

(\(\sqrt {3}\) - \(\pi \))r2 sq. cm

(\(\frac{\sqrt {3}-π}{2}\)) r2 sq. cm

\(\frac{2\sqrt {3}-π}{2}\) r2 sq. cm

Correct Answer:

\(\frac{2\sqrt {3}-π}{2}\) r2 sq. cm

Explanation:

Joining centres of three circles we get equilateral triangle ABC

AB = AC = BC = 2r

shaded area = Ar. of equi ΔABC - Ar. of 3 sectors inside the ΔABC

                 = \(\frac{\sqrt {3}}{4}\) × (side)2 - 3 × ( πr2 \(\frac{θ}{360}\) )

                 =  \(\frac{\sqrt {3}}{4}\) (2r)2 - 3 × (πr2 \(\frac{60}{360}\))

                 =  \(\frac{\sqrt {3}}{1}\) r2 - \(\frac{πr^2}{2}\) 

                 =  \(\frac{2\sqrt {3} - π}{2}\) rsq. cm