VALID – (adjective), means that something is true or alright for the purpose at hand. “The valid answer to this sum is 10.” “His passport is valid for Germany” means that his passport is alright for him to travel into Germany.” That he had an accident and went to hospital is a valid excuse for his not being at school. “The opposite of valid is INVALID.
VALUE – (noun) 1. The value of something is what a thing is worth. “Gold has a high value.” 2. You say you got value for your money then you mean the thing you bought had a low price considering its quality. 3. To value – (verb) something means to estimate what the value of that thing is. When a person wants to get a loan from a bank or building society to buy a house the house has to be valued before the amount of the loan can be worked out. 4. If you say you value a person’s friendship then that means that the friendship is important to you and that you place a high value on it.
VARIABLE – (adjective) 1. Variable means something that changes. “The weather is variable, sometimes it rains and soon after the sun shines. “ 2. In maths a variable is the name given to a number that can change. For example what is the value of ax if a is 4 and x is 2, 4, 6 & 8? The answers are 8, 16, 24 & 32. Here x is a variable and a is a constant. In ax&>2 &> + bx + c = y, x is the independent variable and y is the dependent variable or in y = x&>2 &> + x + 5, y is the dependent variable and x the independent variable. See CONSTANT & CO-EFFICIENT.
VARIATION – (noun) means the amount that a thing changes. See VARY. “The variation between the temperature at night and during the day is about 10 degrees at this time of the year.
VARIOUS – (adjective) means a number of different things. “He looked at various cars before he chose this one. People have various ideas on what the best thing to do is.
VARY – (verb) means to change. “The price of food will vary from one shop to another.
VAT – (noun) stands for Value Added Tax. Value Added Tax has taken the place of General Sales Tax. Both these taxes are taxes on goods that are bought. See TAX.
VECTOR – (noun) In life the size or amount of some things can be described with a number alone. For example 5 apples or 10 children. But some things have got a size and a direction. For example if you say a car is going 100 kph that does not tell you in which direction it is going. You can say you were pushed with a force of 10 kg, but that does not say in which direction you were pushed. In maths the extra information about the direction is given by using a vector. A vector is shown by an arrow. The length of the arrow shows how big it is and the way in which the arrow is pointing shows the direction. See diagram 4.
VERB – (noun) A word is called a verb if it tells about things being done. For example clean, learn, play are verbs. He must clean the floor and learn his homework before he can play with his friends.
See ACTIVE VOICE & PASSIVE VOICE.
VERTEX – (Plural: vertices) – (noun) The vertex of a triangle is the point at a corner of a triangle. Usually when you speak of the vertex of a triangle you mean the top corner. The vertex of a pyramid – (or a cone) is the top point of the pyramid – (or con e) See Diagram 21. The vertex of an angle is the point where the two sides of the angle meet. See diagrams 5 & 14.
VERTICAL – (adjective) means upright. A vertical line will be at right angles to a horizontal line. See HORIZONTAL & RIGHT ANGLES.
VERTICALLY OPPOSITE ANGLES – (noun) See diagram 3.
VIEW – (verb) 1. To view means to look at and see what is there or what is happening. “When you travel in S Africa there are many beautiful places to view. I am going to view TV tonight. “2. A view – (noun) is what you can see when you look. “ There is a nice view from that window because it faces Table Mountain. ” 3. A viewpoint is a point from which to view. Everyone views something from his own viewpoint because everyone cannot be in the same place at the same time. “From my viewpoint it looked as if John hit Peter first.” 4. Viewpoint also means a way of thinking about something. “Everyone looks at life from his own viewpoint and decides what he likes and dislikes from his own point of view.” 5. If you say with a view to doing something it means with the purpose of doing that thing. “He came to the town with the view to get a job.” 6. In view means within one’s sight. “He walked around from behind the corner and is now in view. “ 7. In view of means taking into consideration. See CONSIDERATION. “In view of the bad weather we have decided not to go swimming.
VICE VERSA means ‘the other way around also’. “John loves Joan and vice versa.” This means that Joan also loves John. “Mary cuts Susan’s hair and vice versa.
VOCABULARY – (noun) 1. Vocabulary means the words that a person knows and uses. You would say that, a person who knew a lot of words in a language has a large vocabulary. 2. Vocabulary is also the name for a collection of words with their meanings like a small dictionary. See DICTIONARY & GLOSSARY.
VOICE – (noun) 1. Voice is the name of the sound that one makes through one’s mouth when speaking or singing.” She has a beautiful voice. “2. In grammar it means a form of a verb that shows whether the verb is active or passive. See ACTIVE VOICE & PASSIVE VOICE.
VOLUME – (noun) 1. Volume means an amount of space. “The volume of a ball 1 centimetre” “diameter is less than the volume of a ball 2 centimetres in diameter.” 2. A volume is also another name for a book. “He had written so many stories that when they were printed they occupied two volumes”. 3. Volume also means amount. “This shop is very busy and does a big volume of” “business”. 4. It means also the amount of sound. “Please turn down the volume on your radio because I can’t hear what you are saying”. See Appendix II.12 for some volume formulae.
VOTE – (noun) A vote is a special kind of choice. For example if a group of people want to choose a leader they can decide to use the method of voting. In this method each person in the group has one vote. Let us say there are 19 people in the group and person A wants to be the leader and also person B wants to be the leader. They then put it to the vote. Person A and person B do not vote. This leaves 17 people who can each cast one vote. The man who gets more votes than the other is the one who wins. I f 9 vote for A and 8 vote for B then A becomes the leader. When a person uses his vote to choose something it is called casting his vote.
VOWEL – (noun) A, E, I, O & U are the vowels in the English language. They are called vowels because of the way they are spoken. If you make these sounds you will find that the sound is not blocked by the lips, teeth or tongue. Y is also sometimes used as a vowel like in the word bicycle.