Post on 15-Apr-2017
CIRCLE
Introduction
-2-dimension
-Circular geometry shape
- Set of all point in the plane
A circle is…
Constructing a Circle
Compass is use to create a Perfect Circle with accurate measurements
-To make sure the r (radius) and the d (diameter) are the same at all points
CircleArc-A closed segment of a curve
Sector-A region of a circle which is "cut off" from the circle by a chord
Segment-A portion of a disk enclosed by two radii and an arc
CircleRadius-A distance from the center of the circle to any point of the circumference
Diameter-A distance between two point passing through the center
Circumference-Linear distance around the edge of a closed curve
Piiiiiiii…
Do You Know…Pi is a irrational number since its value is not proportion
Pi has 18 digit decimal place
-which is 3.141592653589793238
Circumference
In which π=22/7 or 3.142
-C=2πr or πd
CircumferenceExample: You walk around a circle which has a diameter of 100m, how far have you walked?
Distance walked = Circumference = π × 100m= 314m (to the nearest m)
-Using the formula of πd
Arc Length
s=arc length of the circle
r=radius
0=degree/radian (converted)
Arc, s=r0
Arc Length
s=r0
s=9(1.05 rad)
s=9.424 cm
Example:
Area of the Sector
s=sector of the circle
r=radius
0=degree/radian
Area of the Sector
s=1/2r2 0
s=1/2(24) 2 (2.095 rad)
s=603.072 cm2
Example:
Area of the SegmentArea of Segment=Area of sector-Area of triangle
r2(0-sin 0)r=radius
0=degree/radian
Area of the Segment
s=1/2r2 (0-sin 0)
s=1/2(7) 2 (1.746 rad)-sin (1.746 rad)
s=42.01 cm2
Example:
SPHERE
Introduction
A sphere is…-3 Dimension
-Circular in shape
-Rounded ball surface completely
Surface Area
A=4πr2
A=Surface area
r =Radius
Surface Area
A=4πr
A=4(22/7)(5) 2
A=314.29cm2
Volume
V= πr3V=Volume
r=radius
Volume
V=4/3 (22/7)(8)3
V=2145.52cm3