if the perimeter of a protractor is 72 cm, calculate its area.

P=  πr+d

72 = πr+ 2r

72 = 22/7r + 2r

72 = 22r+14r/7

504=36r

r= 504/36

r= 14 cm.

Area = πr^₂

22/7*14*14 = 22*2*14 = 616 cm ^{2 .}

 A protractor is semicicrular in shape.

=> Perimeter = pi(r) + base

=> Perimeter = pi(r) + 2r

=> Perimeter = r(2 + pi)

=> r(2+pi) = 72

=> r(2 + 22/7) = 72

=> r( 36/7) = 72

=> r = 72 X 7/36

=> r = 2X7

=> r =14cm

Area = 1/2pi(r²)

= 1/2 X 22/7 X 14²

= 22/14 X 196

= 22 X 14

= 308cm²

@Riya you got the radius correct but its a semi-circle not a circle :)

As protector is a semicircle, so its perimeter = perimeter of half of circle + 2(radius).As Circle of radius R has circumference of 2R so circumference of semicircle = RHence the perimeter = R + 2R = 72cm.so R(+2) = 72R = 72/(+2) = 14.007cmSo the Area of the semi-circle = R²/2 = 3.14 ⨯(14.00)²/2 =307.28cm²

r + d = 72 ( d, since the base consist of a diameter)

= r + 2r= 72

=22/7r + 14/7r = 72

=36r/7 = 72 ,

=36r = 504

= r= 14 cm

area of semi circle= r²

= 22/7 x (14)²

= 22/7 x 196

= 22 x 28

= 616 cm²

pie symbol didnt show up :/ ,

pie*r + d = 72 ( d, since the base consist of a diameter)

= pie*r + 2r= 72

=22/7r + 14/7r = 72

=36r/7 = 72 ,

=36r = 504

= r= 14 cm

area of semi circle= pie*r²

= 22/7 x (14)²

= 22/7 x 196

= 22 x 28

= 616 cm²