SS1: MATHEMATICS - 3RD TERM
-
Geometry (Triangles & Polygon) I | Week 11 Topic
-
Geometry (Triangles & Polygon) II | Week 22 Topics|1 Quiz
-
Geometry (Triangles & Polygon) III | Week 3 & 42 Topics|1 Quiz
-
Trigonometry I | Week 5 & 62 Topics
-
Trigonometry II | Week 6 & 73 Topics|1 Quiz
-
Trigonometry III1 Topic|1 Quiz
-
Mensuration (Plane Shapes) | Week 81 Topic|1 Quiz
-
Mensuration II2 Topics|1 Quiz
-
Mensuration III | Solid Shapes4 Topics|1 Quiz
-
Statistics | Week 92 Topics|1 Quiz
Area of Sector

Recall, the area of a circle is given as \( \scriptsize \pi r^2 \)
In general, the area of a sector of a circle is proportional to the angle of the sector as shown in the diagram above i.e. the area of the sector XOY is \( \frac{\theta}{360^o} \) of the whole circle
i.e. Area of Sector XOY = \( \frac {θ}{360} \scriptsize \: \times \: \pi r^2 \)
Example 1.3.1:
A pie chart is divided into four sectors as shown in the diagram below. Each sector represents a percentage of the whole. The two larger sectors are equal and each represents X%. What is the angle subtended by one of those larger sectors? (WAEC)

Solution:
Note: x% + x% + 21 + 9 = 100%
i.e. 2x% = 100 – 30
i.e. x% = \( \frac{70}{2}\) = 35%
x% = 35%
by proportions 35% ≡ x°
100% = 360º
x° = \( \scriptsize 36^o \: \times \: \normalsize \frac{35}{100} \\ \scriptsize 18^o \: \times \: 7^o \\ \scriptsize 126^o \)
Example 1.3.2:
In the diagram below, ABCD is a rhombus with dimensions as shown BXD is a circular arc with centre A. Calculate the area of the shaded section to the nearest cm2.

Solution
You are viewing an excerpt of this Topic. Subscribe Now to get Full Access to ALL this Subject's Topics and Quizzes for this Term!
Click on the button "Subscribe Now" below for Full Access!
Subscribe Now
Note: If you have Already Subscribed and you are seeing this message, it means you are logged out. Please Log In using the Login Button Below to Carry on Studying!
Love 💕 it
actually i love it also
hi guys
are you there