LESSON TEN (27 JULY 2020) GEOMETRY
GOOD DAY GRADE 8'S,
TODAY’S WORK IS FROM THE TEXTBOOK, CHAPTER 12.
Lets start with a few basic vocab, these are concepts that have been introduced to you in primary school.
COMPLEMENTARY adds up to 90 degrees, SUPPLEMENTARY adds up to 180 degrees.
In Geometry, adjacent means next to.
PERPENDICULAR is when lines meet at a 90 degree angle to each other.
PARALLEL is when lines are equi-distant apart, they have no chance of ever intersecting with each other.
INTERSECTING is when lines pass through each other, at this point the lines create angles. These angles are not always 90 degrees to each other. (maybe try this by using a ruler and drawing two intersecting lines, then take a protractor and measure these angles that have been created)
The interesting thing about intersecting lines is that when two lines do intersect, they create vertically opposite angles, (see page 156). ANGLES THAT ARE VERTICALLY OPPOSITE EACH OTHER ARE EQUAL TO EACH OTHER.
1. Angles less than 90 degrees are called ACUTE ANGLES.
2. Angles equal to 90 degrees are called RIGHT ANGLES.
3. Angles more than 90 degrees but less than 180 degrees are called OBTUSE ANGLES.
4. Angles on a straight line add up to 180 degrees. These are called STRIAGHT ANGLES.
5. Angles that are more than 180 degrees but less than 360 degrees are called a REFLEX ANGLE.
6. Angles that go around a point are called a REVOLUTION.
7. Angles also arise from parallel lines that have a transversal cutting through them. A transversal is a line that cuts two lines, hence creating angles. The angles are called corresponding, alternate and co-interior angles based on their positions. When parallel lines are cut with a transversal, the three types of angles have particular properties. Look at the notes attached. Think FUN,
F = These are corresponding angles, and corresponding angles are EQUAL when lines are parallel.
U = these are co-interior angles, and these angles are SUPPLEMENTARY, ADDS UP TO 180 DEGREES when lines are parallel.
N – These are alternate angles, and alternate angles are EQUAL when lines are parallel.
When working with the activities that come with this section, the most important thing to remember is that every time that you answer the questions, a reason needs to be given. Follow the examples carefully. Contact your teacher if you are unsure.
I have attached notes to help you, as this program does not allow me to put in drawings.
Please read through all these notes and if possible, it is highly recommended that you copy these notes into your books. Firstly, it will allow you to have access to the information when working with other lessons that follow. Also rewriting will help you remember the information.
WORK TO BE DONE IN EXERCISE BOOKS:
ACTIVITY 12.1 (pg 157) and ACTIVITY 12.2 (pg 159) OF THE TEXTBOOK.
DUE: REMEMBER ANSWERS DONE IN YOUR EXERCISE BOOKS MUST BE SENT TO YOUR TEACHERS, FROM THERE WE WILL SEND YOU THE MEMO. LESSON TEN IS DUE NO LATER THAN 30 JULY 2020 @ 15:00. WHATSAPP MESSAGES ARE TO BE SENT ONLY BETWEEN 08:00 AND 15:00 FROM MONDAY TO SATURDAY PLEASE.
***PLEASE ADD THE LESSON NUMBER TO YOUR MESSAGE***
THIS MEANS WHEN SENDING THE PICS, START OF BY STATING YOUR NAME, ADMIN NUMBER AND THE LESSON NUMBER WITH THE DATE:
EXAMPLE: Ayanda Duma, Gr 8B, answers for lesson six(22 June 2020)
NB: If you have not been issued a textbook, please contact me (Mrs Maharaj) urgently!
Details are below:
Mrs Makwara 071 809 2055 firstname.lastname@example.org
Mrs Cassim 084 786 2585 email@example.com
Miss Thwala 083 787 3976 firstname.lastname@example.org
Mrs Hlatshwayo 074 705 6775 email@example.com
Mrs Maharaj 073 5581246 firstname.lastname@example.org
Mr Cele 079 622 1676 email@example.com