Question

The area of a triangle of length 21 cm and diagonal 29 cm is
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Answer 1

Answer:

The area of a rectange = 420 cm^{2}cm

2

Step-by-step explanation:

Given,

The length of rectangle (l) = 21 cm and

The diagonal of of rectangle (d) = 29 cm

Let the breadth of rectangle = b cm

To find, the area of a rectange = ?

We know that,

The diagonal of of rectangle = \sqrt{l^{2}+b^{2}}

l

2

+b

2

⇒ \sqrt{21^{2}+b^{2}}

21

2

+b

2

= 29

Squaring both sides, we get

⇒ 21^{2}+b^{2}=29^221

2

+b

2

=29

2

⇒ b^{2}b

2

= 841 - 441 = 400

⇒ b^{2}b

2

= 20^{2}20

2

∴ The breadth of rectangle = 20 cm

The area of a rectange = Length(l) × Breadth (b)

= 21 cm × 20 cm

= 420 cm^{2}cm

2

Thus, the area of a rectange = 420 cm^{2}cm

2