Question

the diameter of a semi-circular protractor is 28 cm, then find its perimeter. ​

Answer 1

22cm

Step-by-step explanation:

diameter=28cm, radius=28/2=14cm, perimeter=1/2×22/7×14=22cm

Answer 2

Given: Diameter of a semi-circular protractor = 28 cm

To find: Perimeter of the protractor

Solution: According to the given question,

Diameter of the semi-circular protractor = 28 cm

.: Radius = Diameter/2

               = 28/2 = 14 cm

.: Perimeter of semi-circle = πr + 2r

[Semi-circle is half of a circle. It's perimeter includes half of a circle's perimeter i.e., half of 2πr which is πr and diameter]

[π = 22/7, r = 14 cm]

Perimeter of semi-circular protractor = $\frac{22}{7}$ x 14 + 2 x 14

                                                                = 22 x 2 + 28

                                                                = 44 + 28 = 72

Therefore, the perimeter of semi-circular protractor is 72 cm.