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.