FOCUSB
2.
Look at the figure and say which lines are;
Geometry Fundamental signs:
1 A Z
is parallel
is perpendicular
a triangle
an angle
degree
minute
second
1. Look and read:
Lines
a curved line a curve
an oblique line
a point
a segment (line)
a (straight) horizontal line
h
a (straight) vertical line
a ray
These are parallel lines, a is parallel to b. They are equidistant. A straight line drawn across a set of two or more parallel lines is called a transversal. Lines c and b intersect at the point P.
These are perpendicular {orthogonal) tines. p is perpendicular to q
a)	vertical
b)	transversal
c)	parallel
d)	oblique
')	horizontal
0	curved
g)	straight
h)	perpendicular
Q D
3.   Using the words you have learned, describe the following capital letters: 'Example: H - Letter H has two parallel vertical lines and one horizontal line.
a) K
b) B
c) M
d) E
e) I
f) L
g) A
h) X
i) Z J) o
4. Which word (in capital letters) is being described below?
First letter
One full-length perpendicular line is joined at the top and at its centre point by two parallel lines, the former slightly longer than the latter, extending to the right horizontally.
Second letter
A symmetrical, wedge-shaped figure: two straight but oblique iines slanting down to the base from a common point at the top; these are bisected by a single horizontal line.
Third letter
A long vertical line is connected at two points - at the top and halfway down - to a curved, semi-circular line running to the right. From the centre intersection a sloping line drops to the baseline at an angle 45 degrees to the perpendicular, again to the right.
5. Complete the following sentences:
a) Lines may be................or curved..............lines may be divided into three
groups: vertical,..........and...................
b) Pairs of lines may be divided into two groups: those which..........and those which
are..............at all points, which are called..............lines.
5. Look at these figures:
Plane figures
n o
a pentagon
a hexagon
a heptagon
an octagon
a decagon
A triangle has three sides and three angles. A triangle is a three-sided figure.
Now make similar statements about the other figures.
6. Look and read:
A BCD is a square. It is a four-sided figure. All its sides are equal. AH its angles are right angles. Opposite sides are parallel.
Now describe these figures:
w
Y Q
' a right-angled triangle
an isosceles triangle
an equilateral triangle
a rhombus
a parallelogram
A__._B
a trapezium
Section 2 Development
10. Look and read:
AD is an altitude of the triangle. BC is the base. What is the area of A ABC?
AD is equal to EH and BC is equal to FG.
The altitudes of the two triangles are equal and so are the bases.
___\H   Therefore the areas are the same
A ABC has the same area as A EFG.
Now describe the following pairs of triangles:
C E
congruent triangles
similar triangles
11. Compare these figures, saying whether they are congruent, similar or have the same area:
12. Look and read A
B P C
S
B
In square ABCD, the diagonals intersect at 0.
OA = OC and OD = OB. The diagonals bisect each other.
AOB = 90°. The diagonals intersect at right angles^
DAO = BAO. The diagonals bisect the angles.
Now complete these tables:
AC = BD. The diagonals are equal.
AB = DC. The opposite sides are equal,
AB//DC. The opposite sides are parallel.
	Opposite sides equal	Opposite sides parallel	Diagonals bisect each olher	Diagonals bisect angles	Diagonals intersect at right angles
Square	/	/	/	/	/
Rhombus					
Parallelogram					
Trapezium					-----------
Regular hexagon					
Diagonals equal
	Angles equal	Sides equal	Areas equal
Congruent figures			
Similar figures			
a) Divide this triangle into three figures with equal areas, using two straight lines.
I
b) Divide this figure into:
i) two congruent figures
ii) three congruent figures
iii) four congruent figures
a} equilateral
b) equiangular
c) regular
oo
Polygons (4:13)
http.V/learner.org/vod/vod window.html?pid-1801 Listen to and watch the video and answer questions.
1) What was discussed in the previous lesson?...................
2) What is the aim of this lesson?........................................
3) What is a polygon?...........................................................
4) What was wrong with the first definition of a polygon?.
5) What does it mean „polygons are closed"?.....................
6) Why is a circle not a polygon?.........................................
7) What is wrong with two other shapes?...........................
8) Why is X not a polygon?...............................................
Look at these pictures and decide whether the shapes are polygons or not. Try to explain why.
c
I
K I
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