Solution of NCERT Exercise 11.2

Perimeter and Area 7th Math

Solution of NCERT Exercise 11.2

Question (1) Find the area of each of the following parallelogram.

(a)

class 7th math Perimeter and area solution of ncert exercise 11.2-1-a

Solution:

Given, Height of the parallelogram = 4 cm

Base of the parallelogram = 7 cm

∴ Area of parallelogram = ?

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 7 cm × 4 cm

= 28 cm2

Thus, Area of given parallelogram = 28 cm2 Answer

(b)

class 7th math Perimeter and area solution of ncert exercise 11.2-1-b

Solution:

Given,

Base of the parallelogram = 5 cm

Height of the parallelogram = 3 cm

∴ Area of parallelogram = ?

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 5 cm × 3 cm

= 15 cm2

Thus, Area of given parallelogram = 15 cm2 Answer

(c)

class 7th math Perimeter and area solution of ncert exercise 11.2-1-c

Solution:

Given,

Base of the parallelogram = 2.5 cm

Height of the parallelogram = 3.5 cm

∴ Area of parallelogram = ?

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 2.5 cm × 3.5 cm

= 8.75 cm2

Thus, Area of given parallelogram = 8.75 cm2 Answer

(d)

class 7th math Perimeter and area solution of ncert exercise 11.2-1-d

Solution:

Given,

Base of the parallelogram = 5 cm

Height of the parallelogram = 4.8 cm

∴ Area of parallelogram = ?

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 5 cm × 4.8 cm

= 24 cm2

Thus, Area of given parallelogram = 24 cm2 Answer

(e)

class 7th math Perimeter and area solution of ncert exercise 11.2-1-e

Solution:

Given,

Base of the parallelogram = 2 cm

Height of the parallelogram = 4.4 cm

∴ Area of parallelogram = ?

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 2 cm × 4.4 cm

= 8.8 cm2

Thus, Area of given parallelogram = 8.8 cm2 Answer

Question (2) Find the area of each of the following triangles:

(a)

class 7th math Perimeter and area solution of ncert exercise 11.2-2-a

Solution:

Given, Base of the triangle = 4 cm

And, Height of the triangle = 3 cm

Thus, Area of the given triangle = ?

We know that,

Area of a triangle = `1/2xx` Base × Height

∴ Area of the given triangle = `1/2xx` 4 cm × 3 cm

= 2 cm × 3 cm

= 6 cm2

Thus, Area of given triangle = 6 cm2 Answer

(b)

class 7th math Perimeter and area solution of ncert exercise 11.2-2-b

Solution:

Given, Base of the triangle = 5 cm

And, Height of the triangle = 3.2 cm

Thus, Area of the given triangle = ?

We know that,

Area of a triangle = `1/2xx` Base × Height

∴ Area of the given triangle = `1/2xx` 5 cm × 3.2 cm

= `1/2xx` 16.0 cm cm2

= 8 cm2

Thus, Area of given triangle = 8 cm2 Answer

(c)

class 7th math Perimeter and area solution of ncert exercise 11.2-2-c

Solution:

Given, Base of the triangle = 3 cm

And, Height of the triangle = 4 cm

Thus, Area of the given triangle = ?

We know that,

Area of a triangle = `1/2xx` Base × Height

∴ Area of the given triangle = `1/2xx` 3 cm × 4 cm

= `1/2xx12cm^2`

= 6 cm2

Thus, Area of given triangle = 6 cm2 Answer

(d)

class 7th math Perimeter and area solution of ncert exercise 11.2-2-d

Solution:

Given, Base of the triangle = 3 cm

And, Height of the triangle = 2 cm

Thus, Area of the given triangle = ?

We know that,

Area of a triangle = `1/2xx` Base × Height

∴ Area of the given triangle = `1/2xx` 3 cm × 2 cm

= 3 cm × 1 cm

= 3 cm2

Thus, Area of given triangle = 3 cm2 Answer

Question (3) Find the missing values:

S. No.BaseHeightArea of the Parallelogram
a. 20 cm–246 cm2
b.–15 cm164.5 cm2
c.–8.4 cm48.72 cm2
d.15.6 cm–16.38 cm2

Solution:

(a) Given,

Base of the parallelogram = 20 cm

Area of the parallelogram = 246 cm2

∴ Height of the parallelogram = ?

Let height of the parallelogram = h

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 20 cm × h

⇒ 246 cm2 = 20 cm × h

⇒ 20 cm × h = 246 cm2

`=> h = (246 cm^2)/(20 cm)`

⇒ h = 12.3 cm

Thus, height of the parallelogram = missing value = 12.3 cm Answer

(b) Given,

Height of the parallelogram = 15 cm

Area of the parallelogram = 154.5 cm2

∴ Base of the parallelogram = ?

Let base of the parallelogram = b

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = b × 15 cm

⇒ 154.5 cm2 = b × 15 cm

⇒ b × 15 cm = 154.5 cm2

`=> b = (154.5 cm^2)/(15 cm)`

⇒ b = 10.3 cm

Thus, base of the parallelogram = missing value = 10.3 cm Answer

(c) Given,

Height of the parallelogram = 8.4 cm

Area of the parallelogram = 48.72 cm2

∴ Base of the parallelogram = ?

Let base of the parallelogram = b

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = b × 8.4 cm

⇒ 48.72 cm2 = b × 8.4 cm

⇒ b × 8.4 cm = 48.72 cm2

`=> b = (48.72 cm^2)/(8.4 cm)`

⇒ b = 5.8 cm

Thus, base of the parallelogram = missing value = 5.8 cm Answer

(d) Given,

Base of the parallelogram = 15.6 cm

Area of the parallelogram = 16.38 cm2

∴ Height of the parallelogram = ?

Let height of the parallelogram = h

We know that,

Area of a parallelogram = Base × Height

∴ Area of given parallelogram = 15.6 cm × h

⇒ 16.38 cm2 = 15.6 cm × h

⇒ 15.6 cm × h = 16.38 cm2

`=> h = (16.38 cm^2)/(15.6 cm)`

⇒ h = 1.05 cm

Thus, height of the parallelogram = missing value = 1.05 cm Answer

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