Basic Geometrical Concepts

Here we will recall about the basic geometrical concepts.

Basic Geometrical Concepts:

Axiom: It is a proposition that is not proved but considered to be self-evident or subject to necessary decision. Its truth is taken for granted and serves as a starting point for deducing and concluding other truths.

For Example:

• Whole is greater than the part.

• Things that are equal to same thing are equal to one another.

Statement: It is a question that is definitely true or definitely false.

For Example:

• Every triangle has three sides. This statement is true.

• No prime number is even. This statement is false.

Theorem: A formula that is provable without any further assumption is called a theorem. A theorem can be deduced from previously accepted statements such as axiom.

For Example:

• In a right angled triangle, the sum of the squares of two sides is equal to the square of the longest side.

Corollary: Result that is trivial or self-evident from a theorem is known as a corollary. Corollary is simply something which we can prove from some other theorem.

For Example:

Theorem: The sum of interior angles of a triangle is 180°.

Its corollary: The sum of interior angles of a quadrilateral is 360°.

● Lines and Angles

Fundamental Geometrical Concepts

Angles

Classification of Angles

Related Angles

Some Geometric Terms and Results

Complementary Angles

Supplementary Angles

Complementary and Supplementary Angles