CLASS-7
CIRCLE
CIRCLE -
A circle is a two-dimensional geometric shape consisting of all points equidistant from a fixed point called the center. The distance from the center to any point on the circle is the radius. Here are the key properties of a circle:
1. Radius (r):-
- The radius is the distance from the center of the circle to any point on its circumference (boundary).
2. Diameter (d):-
- The diameter is twice the radius and passes through the center, connecting two points on the circumference. It is the longest straight line that can be drawn inside the circle.
d = 2r
3. Circumference (C):-
- The circumference is the distance around the boundary of the circle, calculated using:
C = 2πr
where π (Pi) is approximately 3.14159.
4. Area (A):-
- The area is the amount of space inside the circle, given by:
A = πr2
5. Chord:-
- A chord is any straight line segment whose endpoints lie on the circumference. The diameter is the longest possible chord.
6. Arc:-
- An arc is a portion of the circumference of the circle.
7. Sector:-
- A sector is the area enclosed by two radii and the arc between them. It's like a "slice" of the circle.
8. Central Angle:-
- The angle formed at the center of the circle by two radii is called the central angle. It corresponds to an arc on the circumference.
9. Tangent:-
- A tangent is a line that touches the circle at exactly one point. The tangent is perpendicular to the radius at the point of contact.
10. Secant:-
- A secant is a line that intersects the circle at two points.
11. Concentric Circles:-
- Two or more circles that share the same center but have different radii are called concentric circles.
12. Circumscribed Circle:-
- A circle that passes through all the vertices of a polygon (such as a triangle) is called a circumscribed circle.
The circle is fundamental in geometry and has numerous applications in various fields, from engineering to astronomy.