Let the centre of circular flower bed be O and radius OB = 20 m
Let Rajesh is at point A, and he has to travel tangential path to reach flower bed which is AB as shown
Now we know that radius is perpendicular to point of contact
Hence OB is perpendicular to AB
Hence ∠ABO = 90°
Consider ΔABO
Using Pythagoras theorem
⇒ AB2 + OB2 = AO2
⇒ AB2 + 202 = 292
⇒ AB2 = 292 - 202
Using a2 – b2 = (a + b)(a – b)
⇒ AB2 = (29 – 20)(29 + 20)
⇒ AB2 = 9 × 49
⇒ AB = √(9 × 49)
⇒ AB = ± (3 × 7)
⇒ AB = ±21
As length cannot be negative
⇒ AB = 21 m
Hence Rajesh has to cover 21 m to reach the flower bed along the tangential path.