A circular park of radius $ 20 \mathrm{~m} $ is situated in a colony. Three boys Ankur, Syed and David are sitting at equal distance on its boundary each having a toy telephone in his hands to talk each other. Find the length of the string of each phone.
Given:
A circular park of radius \( 20 \mathrm{~m} \) is situated in a colony. Three boys Ankur, Syed and David are sitting at an equal distance on its boundary each having a toy telephone in his hands to talk to each other.
To do:
We have to find the length of the string of each phone.
Solution:
The radius of the circular park $= 20\ m$
Ankur, Syed and David are sitting at equal distance to each other.
By joining the points, an equilateral triangle $ABC$ is formed.
Produce $BO$ to $L$ which is the perpendicular bisector of $AC$.
Therefore,
$BL = 20 + 10$
$= 30\ m$ ($O$ is the centroid of $\triangle ABC$)
Let $a$ be the side of $\triangle ABC$
$\Rightarrow \frac{\sqrt{3}}{2} a=30$
$a=\frac{30 \times 2}{\sqrt{3}}$
$a=\frac{60 \times \sqrt{3}}{\sqrt{3} \times \sqrt{3}}$
$a=\frac{60 \times \sqrt{3}}{3}$
$a=20 \sqrt{3} \mathrm{~m}$
Hence the distance between each other is $20\sqrt3\ m$.
Related Articles
- A circular park of radius 20m is situated in a colony. Three boys Ankur, Syed and David are sitting at equal distance on its boundary each having a toy telephone in his hands to talk each other. Find the length of the string of each phone.
- A circular park of radius $40\ m$ is situated in a colony. Three boys Ankur, Amit and Anand are sitting at equal distance on its boundary each having a toy telephone in his hands to talk to each other. Find the length of the string of each phone.
- It is proposed to build a single circular park equal in area to the sum of areas of two circular parks of diameters $16\ m$ and $12\ m$ in a locality. Find the radius of the new park.
- A park is in the form of a rectangle $120\ m \times 100\ m$. At the centre of the park there is a circular lawn. The area of park excluding lawn is $8700\ m^2$. Find the radius of the circular lawn. (Use $\pi = \frac{22}{7}$).
- A carpenter makes stools for electricians with a square top of side \( 0.5 \mathrm{~m} \) and at a height of \( 1.5 \mathrm{~m} \) above the ground. Also, each leg is inclined at an angle of \( 60^{\circ} \) to the ground. Find the length of each leg and also the lengths of two steps to be put at equal distances.
- Sides of a triangular field are \( 15 \mathrm{~m}, 16 \mathrm{~m} \) and \( 17 \mathrm{~m} \). With the three corners of the field a cow, a buffalo and a horse are tied separately with ropes of length \( 7 \mathrm{~m} \) each to graze in the field. Find the area of the field which cannot be grazed by three animals.
- A circular park is surrounded by a road 21 m wide. If the radius of the park is 105 m, find the area of the road.
- Show that the diagonals of a square are equal and bisect each other at right angles.
- A toy is in the form of a cone of radius \( 3.5 \mathrm{~cm} \) mounted on a hemisphere of same radius. The total height of the toy is \( 15.5 \mathrm{~cm} \). Find the total surface area of the toy.
- Two chords \( \mathrm{AB} \) and \( \mathrm{CD} \) of lengths \( 5 \mathrm{~cm} \) and \( 11 \mathrm{~cm} \) respectively of a circle are parallel to each other and are on opposite sides of its centre. If the distance between \( \mathrm{AB} \) and \( C D \) is \( 6 \mathrm{~cm} \), find the radius of the circle.
- An wooden toy is made by scooping out a hemisphere of same radius from each end of a solid cylinder. If the height of the cylinder is \( 10 \mathrm{~cm} \), and its base is of radius \( 3.5 \) \( \mathrm{cm} \), find the volume of wood in the toy. (Use \( \pi=22 / 7 \) )
- 50 circular plates each of diameter \( 14 \mathrm{~cm} \) and thickness \( 0.5 \mathrm{~cm} \) are placed one above the other to form a right circular cylinder. Find its total surface area.
- Three girls Ishita, Isha and Nisha are playing a game by standing on a circle of radius $20\ m$ drawn in a park. Ishita throws a ball to Isha, Isha to Nisha and Nisha to Ishita. If the distance between Ishita and Isha and between Isha and Nisha is $24\ m$ each, what is the distance between Ishita and Nisha?
- A toy is in the shape of a right circular cylinder with a hemisphere on one end and a cone on the other. The radius and height of the cylindrical part are \( 5 \mathrm{~cm} \) and \( 13 \mathrm{~cm} \) respectively. The radii of the hemispherical and conical parts are the same as that of the cylindrical part. Find the surface area of the toy if the total height of the toy is \( 30 \mathrm{~cm} \).
Kickstart Your Career
Get certified by completing the course
Get Started
To Continue Learning Please Login
Login with Google