The perimeter of a rectangle whose one side measures 12 cm and diagonal is 20 cm is -
1 point
64 cm
44 cm
56 cm
52 cm
for class 7
Answers
i) Length = 24.5 m
Breadth = 18 m
∴ Area of the rectangle = Length × Breadth
= 24.5 m × 18 m
= 441 m2
(ii) Length = 12.5 m
Breadth = 8 dm = (8 × 10) = 80 cm = 0.8 m [since 1 dm = 10 cm and 1 m = 100 cm]
∴ Area of the rectangle = Length × Breadth
= 12.5 m × 0.8 m
= 10 m2
Answer:
The diagonal of a rectangle divides the rectangle into two right angled triangles.
diagonal ( which is the hypotenuse of the two triangles formed ) = 20 cm
side ( which is one the legs of the two triangles formed ) = 12 cm
Using Pythagoras Theorem:
h² = l² + b²
20² = 12² + b²
b² = h² - l²
b² = 20² - 12²
b² = 400 - 144
b² = 256
b = √256
b = 16 cm
Therefore, the length of the second side of the rectangle ( which is the base of the two triangles formed ) is 16 cm
Perimeter of a rectangle = 2 ( l + b )
= 2 ( 12 + 16 )
= 2 ( 28 )
= 56 cm
Therefore, perimeter = 56 cm.
Answer = c ) 56 cm