**Practice 1 **

Using the words the you have learned,describe the following mathematical symbol.

1) The plus symbol.

2) The minus symbol.

3) The multiplication symbol.

4) The equals symbol.

5) The pi symbol.

**Section 2 Angles **

Look at the figure and say which

lines are :

1) These two lines meet at an angle. This

angle is less than 90o (ninety degrees).

It is an acute angle.

A

They form a right angle. The two

lines are perpendicular to each other.

5. Lines FK and AB intersect at

point X.The angles FXB and

BXK are next to each other, or

adjacent . The sum of these angles

is 180o. They are supplementary

angles.

6) Angles ABY and YBC are equal.

Line BY bisectes angle ABC.

BY is the bisector of angle ABC.

The sum of angles ABY and YBC is

90o. They are complementary angles.

**Practice 3 **

A

P

S T

### B

### o

### O

M N

Describe the lines and angles in the following figures.

1) 2)

A B C

K

F

x y z

4) 3)

P

P

Z

**Unit 8 **

**The triangle**

**Section 1**

A triangel is a three-sided figure. The three sides of a triangel meet at points called

vertices (singular vertex). The vertex at the top a triangle may be called the apex, and

the line at the botton may be called the base.

1) In triangle ABC, line BC is produced to point X. ACB is an interior angle, and

ACX is an exterior angle.

2) This is an isosceles triangle. 3) This is an equilateral triangle. A

B

C

4) This is a right angled triangle.In a

right angled triangle the side

opposite the right angle is called the

hypotenuse.

The theorem of Phytagoras states :

“In a right angled triangle square on

line hypotenuse equal to the sum of

**Section 2 Congruence, similarity **

**And symmetry **

1) If the following parts of two

triangles are equal :

a) Two sides and the included

angle ; or,

b) A right angle, hypotenuse and

side ;or,

c) Two angles and a

corresponding side ; or,

d) All three sides ;

Then the two triangles are

conruent.

2) If two triangles have their

corresponding angles equal, they

are similar.

3) These two triangles are on

either side of an exis of

**Practice 1 **

Describe each triangle, and use your ruler to discover any relation ships between the

triangles (i.e.symetry, similarity or congruence).

**Vocabulary practice **

1) If each of the angles in a triangle is equal to 60o , the triangle is called _________

2) A line which meets another _____________at 90o is called a ____________ line.

3) If two angles of a triangle are equal to 45o , the triangle is called a

_______________________________triangle.

4) If we ______________ a right angle, we have two _____________angles of 45o .

5) Each triangle has three point, or _____________________

1) 2) 3)

4) 5) 6)

7)