Question

the area of a circle is 1386 find its circumference

Answer 1

A/C to formula,
area of circle = πr²
Given area = 1386 sq unit

hence,
1386 = πr²
1386 = 22/7 × r² { π = 22/7}
1386 × 7/22 = r²
126×7/2 = r²
63 × 7 = r²
441 = r² => r² = (21)²
r = 21 unit

hence, circumference of circle = 2πr
= 2 × 22/7 × 21
= 2 × 22 × 3
= 6 × 22
= 132 unit

Answer 2

Area of the circle = 1386
              π r²        = 1386
         22÷7×r²       = 1386
                r²         =  1386×7÷22
                r²         =  441
                r          =  √441
                r          =   21
Circumference of the circle = 2πr
                                            = 2×22÷7×21
                                            = 44÷7×21
                                            = 132