Mensuration, Ex 20F

Question

11. A rectangular sheet of acrylic is 34 cm by 24 cm. From it, 64 circular buttons, each of diameter 3.5 cm, have been cut out. Find the area of the remaining sheet.

Can anyone please answer the questions which are visible? .....

Answer 1

11. Given that, a rectangular sheet of acrylic is 34 cm by 24 cm . 

Area of the acrylic sheet = 34 cm × 24 cm = 816 cm² 

From a rectangular sheet of acrylic, 64 circular buttons, each of diameter 3 . 5 cm , have been cut out. 

So, the diameter of a circular button is 3 . 5 cm . 

Radius of the circular button r = 3.5/2 cm = 35/20 cm = 7/4 cm

Therefore, the area of a circular button = πr² 

= 22/7 × 7/4 × 7/4 cm² 

= 77/8 cm² 

∴ Area of 64 such circular buttons = 64  × 77/8 cm² = 616 cm² 

Area of the remaining acrylic sheet = Area of the rectangular acrylic sheet - Area of 64 circular buttons 

= ( 816 - 616 ) cm² 

= 200 cm² 

Hence, the area of the remaining sheet is 200 cm² .

Answer 2

barbie5878, hello

question 15: I'm confused, with the given hint, there is nothing to do but the math, they give you the required steps?!

In any case, the area of the shaded region comes out to be 154cm²

Please let me know if this helps.