Question

Plz solve these questions , it's very urgent ​

Answer 1

First let's know the formulae :-

• Perimeter of a semicircle :- πr + 2r
• Perimeter of a square :- 4s
• Diameter of a circle :- 2r
• Radius of a circle :- d/2

Solution for i) :-

There are four semicircles attached to a square. So let's first find out the perimeter of the semicircles and then the total perimeter.

Given,d = 3cm.

p = πr + 2r

p = 3.14x1.5 + 3

p = 7.71

Now this is perimeter but we need only outer line.

so,remove 2r from p.

outer line = πr = 3.14 x 1.5 = 4.71.

There are four,so

4 x 4.71 = 18.84

Hence ans is 18.84.

2. solution for ii) :-

There are two small semi circles and one big semi circle. Let's do one by one.

Given,d = 2.8cm.

For bigger one d = 2.8,for two smaller ones d = 1.4,r = 0.7

First small ones:-

p = πr(remember we need only outer line).

p = 3.14 x 0.7

p = 2.2

Two semicircles= 2 x 2.2 = 4.4

Second,the bigger one:-

p = πr

p = 3.14 x 2.8

p = 8.8

Now the perimeter of the given figure :- 4.4 + 8.8 = 13.2

3. solution for iii):-

r = 4.2

p = πr

p = 3.14 x 4.2 = 13.2

But each one is the fourth part of a circle. So,

one part = semicircle part/2 = 13.2/2 = 6.6

There are four of these. So,

6.6 x 4 = 26.4

Hence,26.4 is the answer

4. Solution for IV):-

Three circles.

Circle 1 :-

• p = 2πr
• p = 2 x 3.14 x 2.1
• p = 13.2

Circle 2 :-

• p = 2 x 3.14 x 1.4
• p = 8.8

Circle 3 :-

• p = 2 x 3.14 x 0.7
• p = 4.4

Total perimeter = c1 + c2 + c3 = 13.2+8.8+4+4 = 26.4

HOPE IT HELPS