Question

the perimeter of the protector is 25.7cm find its radius area take(π 3.14)​

Answer 1

• protector is made up of semicircle and diameter

• perimeter of protector = 1/2 circumference + diameter

25.7 = 2πr/2 + d

• Diameter (d) = 2r

•°• 25.7 = πr + 2r

25.7 = 3.14r + 2r

25.7 = 5.14r

r = 25.7 / 5.14 = 5

radius is 15cm

Answer 2

circumference of circle =2πr

but protractor is a semicircle = 2nr/2 = nr

perimeter of the protractor = circumference of semicircle + diameter

25.7 = nr + 2r ( diameter = 2 × radius)

25.7 = 3.14r + 2r

25.7 = 5.14r

r = 25.7/5.14

r = 5cms

radius = 5cms

Area of semicircle = 1/2(πr²)

= 1/2 (3.14 ×5×5)

= 78.5/2

= 39.25

Area = 39.25 cm²