# Maths Revision

• Created by: Zaid
• Created on: 17-11-12 12:33

Angle Relationships:

Vertically opposite angles are equal

Corresponding angles are equal

Alternate angles are equal

Interior angles add up to 180 degrees

-Base angles in an isosceles triangle are equal

Angles that add up to 180 degrees are suplementry

Angles that add up to 90 degrees are complementy

Exterior Angles:

They are the angles the shape has after the sides are extended. polygons exterior angles always add up to 360 degrees so, 360/the number of sides equals the exterior angle.

On a triangle the exterior angle is the sum of the interior angles of the other two vertices.

Interior Angles:
If you know the exterior angle of the poygon then the interior angle is 180-the exterior angle because exterior angle & the interior angle are on a straight line.

To find the sum of the angles inside a polygon we cut the polygon into triangles. the cutting lines must not cross. Working: if we cut the pentagon into 3 triangles. the anglesum in each triangle is 180 degrees. therefore the anglesum of the pentagon is 3 x 180 = 540 degrees

Vocabulary:

Acute angle between 0 and 90 degrees

Right angle 90 degree angle

Obtuse angle between 90 and 180 degrees

Straight 180 degrees

Reflex angles over 180 degrees

1. Number and Algebra.

Multiplying and dividing negative numbers –

E.g.
-2*+4
2*4=8, and - * + is equivalent to -. So -2*+4=-8

-6*-3
6*3=18 and -- is equivalent to +, so -6-3 =+8

+6*-4/-2
+6*4= -24, -24/-2=+12

Key

• = -
• = +
• / - = +

## = +

+-= -

1.
a) -7+8 = 1
j) -5+-4—7=
4.
a) +2*-3= -6
o) -2*+4*-2= -16

HCF and LCM -

E.g.
HCF stands for highest common factor
LCM stands for lowest common multiple

Find the LCM of two numbers
a) 3 and 7 = 21
b) 6 and 9 = 18

A factor is a smaller number that divides exactly into a larger number.
e.g. 2, 3 and 4 are all factors of 12

Find the HCF of two numbers
a)15 and 21 = 3
b) 16 and 24 = 8

Powers and roots –

E.g.
4”3” = 4*4*4 = 64
( Most calculators have a squaring button )

/12.25 = 3.5
(Depending on your calculator, sometimes you type the square root before the number, and sometimes the number comes first. Make sure you can use your calculator.)

Prime Factors-

E.g.
Find the prime factors of 18.
Using a prime factor tree, split 18 into 3*6 and 6 into 3*2.
So, 18 = 2*3*3=2*3”2”
Note that 2*”3” is called index form.

Find the prime factors of 24.
Using the divide method:

2/24
2/12
2/6
3/3
1

So 24=2*2*2*3=2”3”*3

Sequences –