Question

Find AD length, if radius of both semicircle is 2cm

Answer 1

Step-by-step explanation:

We have AD= diameter of circle of radius 6cm=12cm

So, AB=BC=CD=  

3

12

​

=4cm

BD=BC+CD=4+4=8cm

Hence required perimeter=arc of semicircle of radius 6cm+ arc of semicircle of radius 4cm+ arc of semicircle of radius 2cm

=(π×6+π×4+π×2)cm

=12πcm.

Required Area = area of semicircle with AD as diameter+area of semicircle with AB as diameter−area of semicircle with BD as diameter.

=  

2

1

​

×  

7

22

​

×6  

2

+  

2

1

​

×  

7

22

​

×2  

2

−  

2

1

​

×  

7

22

​

×4  

2

 

=  

2

1

​

×  

7

22

​

(6  

2

+2  

2

−4  

2

)

=  

7

264

​

 cm  

2

 

=37.71cm  

2