Question

find the perimeter of the following shapes to 1 d.p. Take π=3.14
solve question 9 (iii) (iv)

Answer 1

Figure 1

radius of both circles = 16 cm / 2

                                   = 8 cm

Perimeter of the figure = Circumference of 2 semicircles + 2 Breadth of the rectangles

                                       = 2 × 1 / 2 × 2 π r + 2 × 3 cm

                                       = 2 π r + 6 cm

                                       = 2 × 3.14 × 8 cm + 6 cm

                                       = 50.24 cm + 6 cm

                                       = 56.24 cm

Perimeter is 56.24 cm

Figure 2

Radius of big semi circle = 8 cm/2

                                         = 4 cm

Radius of small semi - circle = 4 cm / 2

                                               = 2 cm

Perimeter = 4 cm + 3 cm + 3 cm + circumference of the small semicircle + circumference of big semi circle.

= 10 cm + 1/2 × 2 π r + 1/2 × 2 π r

= 10 cm + 3.14 × r + 3.14 × r

= 10 cm + 3.14 × 4 + 3.14 × 2

= 10 cm + 12.56 + 6.28

= 28.84

The perimeter is 28.84 cm

Hope it helps ^__^

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Answer 2

Answer:

Perimeter is the boundary of the figure.

Explanation:

Figure 1:

Perimeter = perimeter of 2 semicircles + breadth of rectangle from both sides

Perimeter of figure = 2πr + 2× breadth

Perimeter of figure = 2 × 3.14 × 8 + 2 × 3

perimeter of figure = 50.24 + 6

perimeter of figure = 56.24 cm

Figure 2:

Perimeter = perimeter of bigger semicircle + perimeter of smaller semicircle + breadth from both sides

Perimeter of figure = πR + πr + 2 × breadth

Perimeter of figure = 3.14 × 4 + 3.14 × 2 + 2 × 3

Perimeter of figure = 12.56 + 6.28 + 6

Perimeter of figure = 24.84 cm

Perimeter of figure 1 = 56.24 cm

Perimeter of figure 2 = 24.84 cm