Question

Twi concentric circles with centre radius 21 cm and 42cm

Answer 1

Hey mate what is the question??

Answer 2

Answer:

not the full question...............answerd by me

first see,

area of the ring = π (42² - 21²) = 4158 cm²

now, we have to remove some parts,

that part = (sector formed by bigger circle) -( sector formed by smaller circle)

             =π (42)²×60°/360 -π(21)² ×60°/360°

             =(π/6)×(42² -21²) = 693 cm²

so the required area = 4158 - 693 = 3465 cm²

see, if small part is shaded then the answer is 693 cm² otherwise if red shaded region you wanna then above answer is correct.