Question

The perimeter of a semicircular protractor whose radius is ‘r’ is​

Answer 1

Step-by-step explanation:

∴ Perimeter of a semicircular protractor is πr+2r. So, option (d) πr + 2r is the correct answer.

Answer 2

Answer: r(π + 2) units

Explanation:

Length of curved boundary = 2πr/2 = πr

Now, length of linear boundary = diameter = 2r

Therefore, perimeter = πr + 2r = r(π + 2)

More:

• Circumference of circ = 2πr
• Area of circ = πr²
• Area of sector = θ/360° × πr² = 1/2 lr

(l = length of arc.)

• Area of quadrant = 1/4 πr²
• Area of segment = Area of sector - area of ∆ so formed
• Area of ∆ so formed = 1/2 r² sinθ
• Area of segment when radius and central angle given = r² {θπ/360° - sin(θ/2) cos(θ/2}.