grade 10 Math lesson

Naming parts-of-a-circle

1. Naming parts of a Circle Naming parts of a circle is practically and technically important in such a way that it systematically allows us to compute areas, linear measure of arcs and circumference, and lengths of segments in a circle.

2. Sector any region in the circle bounded by two radii of a central angle and the arc between their endpoints.   is the arc of the sector in the circle . Thus, the sector in the figure is the area bounded by the radius and radius and arc  

3. Arc a portion of the circle’s circumference. Example: The curve line connecting points and is an example of an arc. This is .  

4. Circular Segment a portion of a circle bounded by a chord of a circle and the arc bounded by the two endpoints of the chord Example: The circular segment is the shaded region/area bounded by and .  

5. Radius distance between the center of the circle and a point on the circle; the plural form of radius is radii Example: The lines , , and are the radii of circle .  

6. Chord a line segment whose endpoints lie on the circle Example: The lines , , and are chords of circle .  

7. Diameter a chord that passes through the center of the circle; the diameter is also the longest chord in a circle Example: The line is the diameter of circle .  

8. Secant a line that intersects a circle in two points Example: The lines and are secants of circle .  

9. Tangent a line that intersects a circle at only one point ; the point where it intersects the circle is called the point of tangency Example: The line is tangent to circle , and the point of tangency is point .  

10. Circumference The distance around the edge of a circle H T L In the figure in the right side, H, T and L are the names of the three circumference.

11. Point of Tangency the point where a tangent line meets the circle c Point C is the point of tangency of the line T with the circle. T

12. Circle a set of all points equidistant from a fixed point called the center of the circle P P is the name of the circle

13. How many degrees is there in the Circle? There is a total of within a circle. Therefore, if in figure , the minor sector CAB is 145°, the remaining major sector is - = 215   A C B   ?

14. Activity 1 Name the following according to what is given in the figure radius= Diameter= Secant= Chord= Tangent circle= Point of tangency=

15. Acitvity 2 Name the following according to what is given in the figure Circle= Centre= Circular segment= Line segment= Circumference = Sector= Arc= K

16. Activity 3 Z R H     1. If the major sector RZH is 262°, what is the measure of the minor sector?

17. 2. If the total area of the circle is 350 sq. cm and the major Circular Segment AB is 330, what is the area of the minor Circular Segment AB? Activity 3